HK1148106A - Disc-shaped high-density recording mediums - Google Patents

Description

Disk-shaped high-density recording medium

Background

Known recording media for recording and reproducing information signals, for example, for recording sound or images include disc-shaped optical recording media and disc-shaped magnetic recording media.

Among these recording media are optical discs (on which information signals are written as micro-irregular lines (irregular lines) by, for example, engraving pits and grooves), phase-change optical discs, permanent magnet (magneto) -optical discs, recording films using the photo-magnetic effect, and hard disks for magnetically writing signals.

In order to form a recording layer on an optical recording medium, in these recording media having micro-irregular patterns, such as grooves or pre-grooves (pre-grooves), associated with information signals, such as data information or tracking servo signals, injection molding of a substrate of plastic material is generally used. In particular, using an injection molding apparatus, the metal mold and a master stamper (stamp) form a wafer-shaped substrate, while the information signal is now described by the master stamper.

To read and record information onto such an optical disc, a laser beam having a wavelength λ is usually passed through a single objective lens of a given numerical aperture NA through a light-transmitting layer of thickness d > λ and focused onto the recording layer with a working distance WD > λ between the objective lens and the surface of the light-transmitting layer. The spot diameter D of the focused laser beam is thus given as D λ/NA. Commercially available discs such as a laser compact disc (CD, λ 780nm, NA 0.45, d 1.2mm), a digital versatile disc (DVD, λ 650nm, NA 0.60, d 0.6mm), a high definition digital versatile disc (HD-DVD, λ 405nm, NA 0.65, d 0.6mm), or a Blu-ray disc (Blu-ray discs) (BD, λ 405nm, NA 0.85, d 0.1mm) are adopting such a far field optical principle. By decreasing λ and increasing NA, the spot diameter D can be decreased, thereby increasing the data density.

However, in such optical far fields (d and WD > λ), the NA of the objective is limited to values < 1.0. To further increase the data density, NA must become larger than 1.0, which can be achieved by near field optics (NFR). An NFR instrument can be implemented using a so-called solid-immersion objective (SIL) (see, e.g., s.m. mansfield, w.r. studenmund, g.s.kino, and k.osato, "High-numerical-aperture lens system for an optical storage head," opt.let. 18, 305ff (1993), the entire contents of which are incorporated herein by reference). For example, in a lens with a far magnetic field consisting of NA < 1.0 and a lens with a refractive index n_SILThe effective numerical aperture NA in a lens system consisting of hemispherical lenses made of the material_effFrom NA.n_SILGiven, if n_SILSufficiently large, this value will exceed 1.0. Another instrument passable diameter D_ApLambda < small holes, which can be achieved either by fiber optics with very narrow end holes (see, e.g., H.Br ü ckl, Physik in unserer Zeit, 28, Jahrgan 1997Nr.2, p 67ff, the entire contents of which are incorporated herein by reference) or by optically non-linear response thin shielding layers (so-called Super resolution enhanced Near Field structures), see, e.g., J.Tominaga, et al, applied Physics Letters, Vol 73(15) 1998.2078-2080, the entire contents of which are incorporated herein by reference).

NFR uses an electromagnetic field with WD < λ between the surface of the lens system or aperture and the surface of the disc or recording layer. For example, in k.saito et al.Technical Digest ISOM 2001, p244ff, has shown that with a working distance WD < 405nm, sufficient light from the evanescent wave of the SIL can be incorporated into the disc so that the NA of the SIL_effCan be increased to above 1.0 of the far magnetic field limit. It has also been shown that the accuracy of the WD must be controlled to a level of several nm to obtain a stable reproduction signal. This is understood to mean that the intensity of the evanescent wave decays exponentially with the distance from the lens surface. To establish such a control mechanism, an effective feedback servo loop is proposed and incorporated by t.ishimoto et al, Technical Digest ISOM/ODS 2002, WC3, p 287ff, the entire contents of which are incorporated herein by reference. Such servo loops are also capable of compensating for fluctuations in WD from modal oscillations (modes) of the turntable (j.i. lee et al, Technical Digest ODS 2006MC4, p 43ff, the entire contents of which are incorporated herein by reference). However, due to the bandwidth limitation of the servo cycle, such compensation only works at lower disc rotational speeds and at low frequency modal oscillations with mode frequencies < 800 Hz. Therefore, there is a limit to the data transfer rate due to the amplitude of the high-frequency modal oscillations of, for example, a monolithic (massive) polycarbonate disk 120mm in diameter and 1.1mm in thickness. The substrate disclosed therein does not meet the requirements of the substrate of the present invention, and in order to improve the intermittent (gap) servo control operation of the disk at high speed rotation, it is necessary to improve, among other things, the high-frequency mode oscillation behavior of the disk.

The modal oscillations being characterized by their mode frequency f_nAccording to f_nAnd (E/p)^0.5(see also equation 1), f)_nRelating to the geometry of the disc and the Young's modulus E and the quantification of the mass density p. The quality factor Q (see equation 2) is related to tan δ by Q ═ 3/tan δ (loss tangent). In this sense, Q can be used as a measure of damping such as tan δ. Low Q means high damping because tan δ is high. In general, E and Q show a clear dependence on the frequency f.

US 6,908,655B2, the entire content of which is incorporated herein by reference, focuses on the effect of low frequency (initial) modal oscillations of about 140Hz, which typically occur in monolithic polycarbonate discs of 120mm diameter and 1.1mm thickness, and is also relevant to far field optical pick-up heads.

WO 00/48172, the entire content of which is incorporated herein by reference, focuses on the initial mode frequency (< 300Hz) behaviour of the disc, it being said that the initial mode frequency should preferably lie outside the rotational operating range of the disc. No solution is disclosed as to the behavior of high-frequency modal oscillations (> ═ 2000 Hz). Comparative example 3, which is presented in the experimental part of the present application on the basis of example 2 of WO 00/48172, shows that a solution implementing the low frequency requirements with respect to damping does not meet the high frequency requirements of the present invention.

WO 2003/005354a1, the entire content of which is incorporated herein by reference, describes specific copolycarbonates (copolycarbonates) to obtain improved damping of the disc, the disclosure differing from the present invention with respect to the chemical structure of the polymer or describing the requirements relating to the low (initial) mode frequency of damping but not the high frequency requirements of the present invention.

Other solutions achieve improved damping at low frequencies (1Hz-16Hz), however they are inadequate for the high-frequency modal oscillation requirements of the present invention as disclosed in US 6,391,418Bl, EP 1158024a1 and US 2004/0265605Al, the entire contents of which are each incorporated herein by reference. US 6,391,418Bl describes a substrate for an information recording medium made of a polycarbonate composition comprising a polycarbonate having a viscosity average molecular weight of 10.000 to 40.000 and a biphenyl, a triphenyl compound or a mixture thereof. EP 1158024a1 describes a vibration-damping thermoplastic resin composition comprising a)50 to 90 wt.% of an amorphous thermoplastic resin having tan δ loss and load deflection temperature of 0,01 to 0,04 of not less than 120 ℃ and b)50 to 10 wt.% of a methyl methacrylate resin, wherein a product molded therefrom has certain physical properties. US 2004/0265605Al describes a vibration damping storage medium for data comprising a substrate comprising at least one polyimide layer and at least one data layer on a physical part of the substrate. This is related to the initial modal (low frequency) oscillations.

Another important feature of NFR is that the coupled light from the evanescent field (couple light) enters the surface of the recording medium through WD < lambda to fully utilize the NA of the SIL_effFor reducing D to λ/NA_eff. For this reason, the real part n of the refractive index of the highest light transmitting layer (upper light transmitting layer) of the recording medium must be larger than NA_eff. Such a layer can be obtained by a high refractive index layer (HRI-coating) which according to the invention forms the surface layer of the recording medium and allows coupling of light of the evanescent-field into the recording medium. The HRI-coating may also be used as a splitting layer between two or more replication layers (reproducing layers) or recording layers. For increasing the storage density by at least a factor of 2 in comparison with the respective far field optics (NA < 1.0), NA_effShould be at least > 1.41 and thus the real part n of the refractive index of the HRI-layer should be at least > 1.41. The prior art, which is devoted to the study of far field optics, cannot explain this.

US 6,875,489B2 or EP 1,518,880a, the entire contents of which are each incorporated herein by reference 1, focus on the discussion of light-transmitting layers having a thickness d > 3 μm, as these embodiments relate to far field optical discs such as BD. Effective NA as in the case of NFR_effAbove 1.0, it is crucial to limit the light-transmitting layer thickness d to small values (e.g., < ═ 3 μm), since it is easier to compensate for, for example, optical aberrations (aberrations) (Zijp et al, proc. of spie vol.5380, p 209 ff).

In addition to the above-described Optical characteristics due to the extremely small WD of the HRI layer and the NFR Optical Pick-Up head (Optical Pick-Up Heads), such HRI layer is also applied as a protective layer for information stored in a recording medium and the Optical Pick-Up head in the case of an accidental head crash. The HRI layer should therefore have a high scratch resistance and a low surface roughness R_aSince the WD is in the range of only a few 10 nm. Also the imaginary part k of the absorption or refractive index of the HRI-layer should be low in order to be able to obtain a sufficiently high reflected light from the multi-stack recording layer separated by the split layers, which may comprise the HRI-layer and achieve a high readout stability. In addition, the first and second substrates are,the prior art does not explain such a complex property profile of the disc structure.

Brief description of the invention

Various embodiments of the present invention provide an optical recording medium of an intermittent servo-controlled NFR disk, in which at least a recording layer and a light transmitting layer are sequentially formed on a substrate, and in which a light transmitting layer surface for recording and/or reproducing an information signal emits light, while the substrate meets specific requirements for young's modulus and damping (Q-factor) at a high frequency of 2000 Hz. Further, various embodiments of the present invention provide the optical recording medium as described above, which has a light-transmitting layer satisfying specific requirements for refractive index, scratch resistance and surface roughness.

The present invention relates to a recording medium having a recording medium for recording various information signals. Such as a wafer-shaped high-density recording medium of a special structure suitable for digital data of a near-field optical pickup.

In intermittent servo-controlled near-field recording and near-field readout, the working distance WD between the lens and the disc surface must be reduced to well below the wavelength λ of the laser and must be controlled within a tight range. There are therefore stringent requirements regarding the high-frequency mode oscillation behavior of the optical disc and the thickness of the optical disc, the optical and mechanical properties of the light-transmitting layer. The present invention shows that a particular choice of disc structure is achieved with suitable materials to solve the above problems.

One embodiment of the present invention includes an optical recording medium comprising a substrate and a recording layer and a light-transmitting layer sequentially disposed on the substrate; wherein the substrate comprises one or more parts selected from the group consisting of injection molded parts (parts), an injection molded sandwich structure having a molded surface layer and a molded core layer, or two UV-bonded injection molded parts, and combinations thereof; and wherein the substrate has a Young's modulus E of at least 2.15GPa and a quality factor of less than 160 when measured according to ASTM E756-05 at 25 ℃ and 2000 Hz.

Brief description of several views of the drawings

The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. To assist in the explanation of the invention, the drawings show representative embodiments that are to be considered exemplary. It should be understood, however, that the present invention is not limited in any way to the precise arrangements and media shown.

In the figure:

FIG. 1 is a graphical representation of a Laser-Doppler-Vibrometer (LDV) set up as described in ASTM E756-05, which can be used to measure Young's modulus E and quality factor of substrates used in various embodiments of the present invention.

Detailed Description

As used herein, the singular terms "a", "an" and "the" are synonymous and can be used interchangeably with "one or more" and "at least one" unless the language and/or context clearly dictates otherwise. Thus, for example, reference to "a resin" herein or in the appended claims may refer to a single resin or to more than one resin. In addition, all numerical values should be understood as modified by the word "about" unless otherwise specifically indicated.

Affecting the modal oscillations of the optical disc at a high frequency may include: increasing its young's modulus E (stiffness), which moves modal oscillations to higher frequencies, thereby reducing its amplitude with a given damping; or to decrease its quality factor Q (increase its damping) to reduce the oscillation amplitude. To overcome the problems described above, the stiffness or damping can be improved as a single parameter or as two parameters.

Various embodiments of the present invention include an optical recording medium including at least a recording layer and a light-transmitting layer. The recording layer and the light-transmitting layer are sequentially formed on the substrate, and light is irradiated from the light-transmitting layer side so as to record and/or reproduce an information signal. The substrate may comprise an injection molded part or have an injection molded sandwich structure with a molded surface layer (skin) and a molded core layer or may comprise two UV-bonded injection molded parts. The substrate has a Young's modulus E of at least 2.15GPa and a quality factor of less than 160 when measured according to ASTM E756-05 at 25 ℃ and 2000 Hz.

The thickness of the light-transmitting layer is preferably from 1nm to less than 3000nm, more preferably from 200nm to less than 2000nm and especially from 500nm to less than 1500 nm.

Substrate material:

examples of suitable substrate materials for forming the substrate include polymers, blends and compounds (filled thermoplastic resin compositions), and substrates that meet the requirements of Young's modulus E and quality factor. However, the polymer resin for the substrate of the present invention is not limited to the following examples.

In the case where the thermoplastic resin itself does not meet the requirements of the bulk injection molded part with respect to young's modulus E and quality factor, mixtures or filled compositions of thermoplastic resins or combinations of thermoplastic resin matrix materials in sandwich structures or in bonded structures may be used.

In addition to the requirements with respect to young's modulus E and quality factor, the thermoplastic resin, mixture or compound should have low water absorption, high heat resistance and should be processable for the optical disc by usual methods such as injection molding, injection compression molding and the like.

Such thermoplastic resins may include polycarbonate resins, acrylic resins, polystyrene resins, and amorphous polycycloolefins (polycycloolefinic) and hydrogenated polystyrene. The thermoplastic resin may also be a mixture of different thermoplastic resins, as well as a mixture of thermoplastic resin(s) compounds with fillers and/or additives.

Polycarbonate resin:

the polycarbonate resin is generally obtained by solution polymerization or melt polymerization of an aromatic dihydroxy compound and a carbonate precursor. Any aromatic dihydroxy compound is acceptable if it meets the above conditions.

Preferred aromatic dihydroxy compounds include compounds of formula (1):

HO-Z-OH (1)，

wherein Z represents a group of formula (1a)

Wherein R is¹And R²Independently of one another denote Hor C₁-C₈Alkyl, preferably H or C₁-C₄Alkyl, in particular hydrogen or methyl, and X represents a single bond, C₁-C₆Alkylene radical, C₂-C₅Alkylidene or C₅-C₆Cycloalkylene radicals which may be substituted by C₁-C₆-alkyl, preferably methyl or ethyl, with the proviso that R if X represents 3, 3, 5 trimethylcyclohexylene¹And R²Represents hydrogen.

More preferably X represents a single bond, a methylene, isopropylidene or cyclohexylidene group or 3, 3, 5 trimethylcyclohexylidene, in particular X represents isopropylidene or 3, 3, 5 trimethylcyclohexylidene.

The aromatic dihydroxy compound is generally known or can be prepared according to generally known methods.

Examples of the aromatic dihydroxy compound include hydroquinone, resorcinol, 4 '-biphenol (biphenol), 1-bis (4-hydroxyphenyl) ethane, 2-bis (4-hydroxyphenyl) propane, 2-bis (4-hydroxyphenyl) butane, 1-bis (4-hydroxyphenyl) -1-phenylethane, 1-bis (4-hydroxyphenyl) cyclohexane, 2-bis (4-hydroxyphenyl) pentane, 4' - (p-phenylenediisopropylidene) diphenol (diphenol), 9-bis (4-hydroxyphenyl) fluorene, 1-bis (4-hydroxyphenyl) -4-isopropylcyclohexane, 2-bis (3-methyl-4-hydroxyphenyl) propane, 1, 1-bis (4-hydroxyphenyl) cyclohexane, 1-bis (4-hydroxyphenyl) -3, 3, 5-trimethylcyclohexane, 9-bis (3-methyl-4-hydroxyphenyl) fluorene and α, α' -bis (4-hydroxyphenyl) m-diisopropylbenzene. Preferred dihydroxy compounds are 2, 2-bis (4-hydroxyphenyl) propane (bisphenol A), 4' - (m-phenylenediisopropylidene) diphenol and 1, 1-bis (4-hydroxyphenyl) -3, 3, 5-trimethylcyclohexane.

The polycarbonate resin may be a homopolycarbonate obtained by homopolymerization of the above-mentioned aromatic dihydroxy compound or a copolycarbonate obtained by heterogeneous molecular polymerization of two or more aromatic dihydroxy compounds. Further, there may be mentioned copolycarbonates obtained by polymerization of the above-mentioned aromatic dihydroxy compound with one or more other dihydroxy compounds.

The reaction by the solution method is usually a reaction between dihydric phenol and phosgene, and is usually carried out in the presence of an acid coupling agent and an organic solvent. As the acid coupling agent, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, or an amine compound such as pyridine is used. As organic solvent, halogenated hydrocarbons, such as dichloromethane or chlorobenzene, are used. To accelerate the reaction, it is also possible to use catalysts such as tertiary amines, quaternary ammonium compounds or quaternary phosphonium compounds, which are illustrated by triethylamine, N-ethyl-piperidine, tetra-N-butylammonium bromide, or tetra-N-butylphosphonium bromide, respectively. Preferably, the reaction temperature is about 0 to 40 ℃, the reaction time is 10 minutes to 5 hours, and the pH during the reaction is not lower than 9.

In the polymerization reaction, an end-capping agent is generally used. These end-capping agents used may be monofunctional phenols. These monofunctional phenols are generally used as end-capping agents for adjusting molecular weight. The obtained polycarbonate resin has its terminals terminated with monofunctional phenol-based groups, so that it is superior in terminal stability to polycarbonate resins not obtained as described above. Monofunctional phenols are typically phenols or lower alkyl-substituted phenols such as phenol, p-tert-butylphenol, p-cumylphenol, isooctylphenol, or long chain alkylphenols such as decylphenol, dodecylphenol, hexadecylphenol, octadecylphenol, eicosylphenol, docosylphenol and triacontylphenol.

The blocking agent is incorporated in an amount to achieve the appropriate molecular weight. The blocking agents may be used alone or in combination.

The average molecular weight of the polycarbonate or copolycarbonate is characterized by the relative solution viscosity of the polymer solution in dichloroethane (measured with an Ubbelhode capillary viscometer, capillary type 0C). The polymer concentration was 5g/l and the measurement was carried out at a temperature of 25 ℃. The relative solution viscosity is in the range from 1.15 to 1.30, preferably in the range from 1.18 to 1.25, particularly preferably in the range from 1.19 to 1.23.

The reaction by the melting method is usually a transesterification reaction between the dihydric phenol and the carbonate ester, and may be carried out by a method comprising mixing the dihydric phenol and the carbonate ester under heating in the presence of an inert gas, and distilling off the formed alcohol or phenol. Although the reaction temperature is different from, for example, the melting point of the alcohol or phenol produced, it is generally 120-350 ℃. During the latter half of the reaction period, the reaction system was depressurized to about 1.33x10³To a pressure of 13.3Pa to promote distillation of the alcohol or phenol formed. The reaction time is usually 1 to 4 hours.

In the carbonates, there are for example C₆-C₁₀Aryl or aralkyl radicals or C₁-C₄Esters of alkyl esters, which may sometimes be substituted, in particular diphenyl carbonate, bis (chlorophenyl) carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate, dimethyl carbonate, diethyl carbonate and dibutyl carbonate. Of these esters, diphenyl carbonate is most preferred.

To accelerate the polymerization, a polymerization catalyst may also be used. Thus, these polymerization catalysts, those conventionally used for esterification or transesterification, for example, alkali metal compounds such as sodium or potassium salts of sodium hydroxide, potassium hydroxide or dihydric phenols, alkaline earth metal compounds such as calcium hydroxide, barium hydroxideOr magnesium hydroxide, a basic nitrogen-containing compound such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, trimethylamine or triethylamine, an alkoxide of an alkali metal or alkaline earth metal, a basic phosphorus-containing compound such as tetraphenylphosphonium phenolate (phenolat) or an organic acid salt of an alkali metal or alkaline earth metal, a zinc compound, a boron compound, an aluminum compound, a silicon compound, a germanium compound, an organotin compound, a lead compound, an osmium compound, an antimony compound, a manganese compound, a titanium compound or a zirconium compound. These catalysts may be used alone or in combination. These catalysts are preferably used in an amount of 1X10 relative to 1 mole of the dihydric phenol as the starting material^-8To 1x10^-3Equivalent weight, more preferably 1X10^-7To 5x10^-4Equivalent amounts are used.

The aromatic polycarbonate resin may contain tri-or more functional aromatic compounds or branched complexing agents (components) in the polymer due to isomerization reaction in polymerization. Examples of the tri-or more-functional aromatic compound preferably include phloroglucin (phloroglucin), pentahydroxyphenol (phloroglucide), triphenols such as 4, 6-dimethyl-2, 4, 6-tris (4-hydroxyphenyl) heptene-2, 2, 4, 6-trimethyl-2, 4, 6-tris (4-hydroxyphenyl) heptane, 1, 3, 5-tris (4-hydroxyphenyl) benzene, 1, 1, 1-tris (4-hydroxyphenyl) ethane, 1, 1, 1-tris (3, 5-dimethyl-4-hydroxyphenyl) ethane, 2, 6-bis (2-hydroxy-5-methylbenzyl) -4-methylphenol and 4- (4- [1, 1-bis (4-hydroxyphenyl) ethyl ] benzene) - α, α -dimethyl-n-benzylphenol, tetrakis (4-hydroxyphenyl) methane, bis (2, 4-dihydroxyphenyl) ketone, 1, 4-bis (4, 4-dihydroxytriphenylmethyl) benzene, trimellitic acid, pyromellitic acid, benzophenone tetracarboxylic acid and its chlorous acid (acids chlorides). Of these compounds, 1, 1, 1-tris (4-hydroxyphenyl) ethane and 1, 1, 1-tris (3, 5-dimethyl-4-hydroxyphenyl) ethane are preferred.

Phosphorus-based heat stabilizers may be added to the thermoplastic resin. Suitable phosphorus-based heat stabilizers are, for example, phosphorous acid, phosphoric acid, phosphonous acid, phosphonic acid and esters thereof. In particular, phosphite compounds such as triphenyl phosphite, trisnonylphenyl phosphite, tris (2, 4-di-t-butylphenyl) phosphite, tridecyl phosphite, trioctyl phosphite, trioctadecyl phosphite, didecyl monophenyl phosphite, dioctyl monophenyl phosphite, diisopropyl monophenyl phosphite, monobutyl diphenyl phosphite, monodecyl diphenyl phosphite, monooctyl diphenyl phosphite, bis (2, 6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, 2-methylenebis (4, 6-di-t-butylphenyl) octyl phosphite, bis (nonylphenyl) pentaerythritol diphosphite and bis (2, 4-di-t-butylphenyl) pentaerythritol diphosphite and phosphate compounds may be specified, such as tributyl phosphate, trimethyl phosphate, tricresyl phosphate, triphenyl phosphate, trichlorophenyl phosphate, triethyl phosphate, diphenyl cresyl phosphate, diphenyl mono-ortho-biphenyl phosphate, tributoxyethyl phosphate, dibutyl phosphate and diisopropyl phosphate. Further phosphorus-based heat stabilizers are, for example, tetrakis (2, 4-di-tert-butylphenyl) -4, 4 '-biphenylene diphosphinate (diphosphonite), tetrakis (2, 4-di-tert-butylphenyl) -3, 3' -biphenylene diphosphinate and bis (2, 4-di-tert-butylphenyl) -4-biphenylene phosphinate. Among these compounds, trisnonylphenylphosphinate, distearylpentaerythritol diphosphite, bis (2, 4-di-tert-butylphenyl) pentaerythritol diphosphite, tris (2, 4-di-tert-butylphenyl) phosphite, triphenyl phosphate, trimethyl phosphate, tetrakis (2, 4-di-tert-butylphenyl) -4, 4' -biphenylenediphosphinate and bis (2, 4-di-tert-butylphenyl) -4-biphenylenephosphinite are preferred. These heat stabilizers may be used alone or as a mixture. The amount of these heat stabilizers is preferably 0.0001 to 0.5 parts by weight, more preferably 0.0005 to 0.2 parts by weight and most preferably 0.002 to 0.2 parts by weight, relative to 100 parts by weight of the thermoplastic resin composition.

Generally known antioxidants may be added to the thermoplastic resins of the present invention to prevent oxidation. An example of an antioxidant is a phenol-based antioxidant. The amount of the antioxidant is preferably 0.0001 to 0.05 wt% based on the thermoplastic resin.

Higher fatty acid esters of monohydric or polyhydric alcohols may optionally be added to the thermoplastic resin of the present invention. By mixing a higher fatty acid ester of a monohydric alcohol or a polyhydric alcohol, releasability from a mold at the time of molding of a thermoplastic resin is improved and releasing force (release load) at the time of molding of an optical disc substrate is made small, thereby making it possible to prevent deformation of the optical disc substrate and pit dislocation (pit dislocation) due to mold release failure. The melt fluidity of the thermoplastic resin is also improved.

The amount of the ester of an alcohol and a higher fatty acid is 0.01 to 2% by weight, preferably 0.015 to 0.5% by weight, more preferably 0.02 to 0.2% by weight, based on the thermoplastic resin.

Additives such as other thermoplastic resins, light stabilizers, colorants, antistatic agents and lubricants may be added to the resin for an optical disk substrate of the present invention in an amount within the range of the transcribability (transcrybilty) and action to reduce warpage in the moisture absorption and moisture desorption steps of the molded disk.

In the preparation of the resin composition of the present invention, it is understood that the mixing of various polycarbonate resins and/or the mixing of a polycarbonate resin with other resins is carried out at the stage of a polymer solution or a molded article such as pellets or granules (pellets). This is not particularly limited. As a means of mixing, in the stage of the polymer solution, a vessel equipped with a stirrer is mainly used, and in the stage of molded articles such as pellets or granules, a drum-type, twin-cylinder mixer (twin-cylinder mixer), a Nauter mixer, a Banbury mixer, an extrusion roll (kneading roll) or an extruder can be used. In any case, any technique may be used and there is no particular limitation.

In the above resin composition, various fillers may be added as additional components to improve rigidity and oscillation damping characteristics. Examples of fillers are glass fibers, glass flakes, carbon fibers, milled fibers, acicular single crystal wollastonite, carbon black, carbon nanotubes (nanotubes), silica particles, titanium oxide particles, alumina particles, talc, mica and other inorganic materials. Heat-resistant organic fillers such as aramid fibers, polyarylate fibers, polybenzothiazole fibers, and aramid (aramide) powder can also be used. When such a component is used, a talc filler and a graphite filler are preferable. Such ingredients are preferably added in an amount of 1 to 30 wt% based on the weight of the resin composition.

The thermoplastic resin composition can be prepared by mixing the various components of the thermoplastic resin composition by a kneader such as a tumbler, a V-mixer, a nauta mixer, a Banbury mixer, an extrusion roll or an extruder. More efficiently, the ingredients are melted and kneaded together by an extruder, particularly a twin-barrel screw extruder.

Acrylic resin:

suitable acrylic resins include polymethylmethacrylate or a copolymer of methylmethacrylate and one or more other ingredients. Examples of such ingredients are alkyl acrylates, such as methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, pentyl acrylate, hexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, dodecyl acrylate, octadecyl acrylate, phenyl acrylate and benzyl acrylate, alkyl methacrylates, such as ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, pentyl methacrylate, hexyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, phenyl methacrylate and benzyl methacrylate, and copolymers thereof. Mixtures of acrylic resins may also be used. Polymethyl methacrylate is the most preferred acrylic resin.

The molecular weight Mw (weight average molecular weight) of the acrylic resin is determined by light scattering, and is preferably 50,000-2,000,000g/mol, more preferably 60,000-1,000,000, most preferably 70,000-500,000 and especially 80,000-300,000 g/mol.

These acrylic resins may also be used in the form of a mixture with the above-mentioned polycarbonates. The amount of acrylic resin in this case is preferably less than 50% by weight, more preferably less than 20% by weight, particularly preferably less than 10% by weight, based on the total composition.

In a mixture with polycarbonate, the acrylic resin may also be an acrylic elastomer. In this case, it comprises as an essential component an acrylate rubber component, optionally a methyl methacrylate copolymerizable therewith, with C₁-C₈Alkyl acrylate of alkyl group and vinyl monomer as copolymer components. In such acrylic elastomers, the amount of methyl methacrylate is from 15 to 65 weight percent based on 100 weight percent of the elastomer.

The acrylate rubber contains C₂-C₁₀Alkyl acrylates and, if desired, styrene, methyl methacrylate or butadiene as a component copolymerizable therewith.

At C₂-C₁₀In the case of alkyl acrylates, 2-ethylhexyl acrylate and n-butyl acrylate are preferred. Such alkyl acrylate is preferably contained in an amount of 50 wt% in 100 wt% of the acrylate rubber. Also preferably, the acrylate rubber is at least partially crosslinked. Examples of the crosslinking agent for crosslinking may be, for example, ethylene glycol diacrylate, butylene glycol diacrylate, ethylene glycol dimethacrylate, allyl methacrylate, and polypropylene glycol diacrylate. Preferably, 0.01 to 3% by weight of these crosslinkers are used in the acrylate rubber.

As a preferred form of the acrylic elastic material, it may preferably be an acrylic rubber component, with methyl methacrylate, with C, optionally copolymerizable therewith in multiple layers₁-C₈Alkyl acrylates of alkyl groups, styrene and vinyl monomers, core-shell structures and multilayer structures obtained upon polymerization. Such acrylic elastic materials may be prepared by any known method, such as block polymerization, suspension polymerization, block-suspension polymerization, solution polymerization or emulsion polymerization.The multilayer structure may also contain components that are not grafted onto the graft base in a multistage polymerization.

These elastomeric acrylic resins, when used in a mixture with the above polycarbonates, are preferably used in an amount of less than 10 weight percent of the total composition. More preferably, it is less than 5 wt%.

Polystyrene resin:

styrene (Styrenic) resins suitable for the various embodiments of the present invention include homopolymers of styrene, copolymers of styrene, or Styrenic thermoplastic elastomers or blends, such as a blend of polystyrene and polyphenylene ether. These materials are used in several forms, but the largest part includes copolymers comprising styrene, isoprene and butadiene. Copolymers include triblock copolymers such as S-B-S, S-I-S, S-EB-S and S-EP-S; alternating block copolymers such as (S-I); grafted block copolymers such as (S-B) and (S-I) and mixtures of triblock/diblock copolymers (e.g., S-B-S/S-B).

These styrene resins can be prepared according to known polymerization rules and by known procedures. Styrene polymers can be prepared, for example, by the method of Houben Weyl, the method of organic chemistry, 4 th edition, Vol.XIV/1, pp.761-841, Georg Thieme-Verlag (1961). They are also commercially available in suitable forms. The free radical procedure is preferred, but ionic polymerization procedures can also be used. The molecular weight Mw of the polymers used according to the invention is generally about 2000, preferably in the range from 5000-. (measured by light scattering; cf. Ullmann's Encyclopedia of Industrial Chemistry, 4 th edition, Vol.15, pp.285-387, Verlag Chemistry 1978).

Homopolymers and copolymers may also be prepared by known procedures. (Cf.H.Rauch-Puntigam, Th.Volker, acrylic and methacrylic compounds, Springer-Verlag 1967). Even if it is possible in principle to prepare them by anionic polymerization or group transfer polymerization (see also o.w.webster et al, j.am.chem.soc, 105, 5706(1983)), the preferred form of preparation is free radical polymerization.

The molecular weight Mw (weight average molecular weight) of the styrenic thermoplastic elastomer, determined by light scattering, is generally higher than 2000 and is generally in the range of 10,000-2,000,000, preferably 20,000-200,000 Dalton.

Moreover, polymers from a group of amorphous polyolefins may also be used. Such polymers result from the polymerization of cyclic olefins, from the ring-opening polymerization of cyclic olefins and also from specially hydrogenated polyolefins such as hydrogenated polystyrene-based polymers.

Polycycloolefin resin:

suitable polymers of cyclic olefins include, for example, the polymerization products of olefins and norbornene (norbenene) structures such as norbornene itself, tetracyclododecene (tetracyclodecene), vinylnorbornene or norbornadiene. Suitable polycycloolefin resins also include copolymers of such olefins with norbornene structures bearing olefins, for example, copolymers of ethylene and norbornene and ethylene and tetracyclododecene. Such products are described, for example, in Japanese patent application Kokai (Laid-Open) No.292,601/86, Japanese patent application Kokai (Laid-Open) No.26,024/85, Japanese patent application Kokai (Laid-Open) Nos.19,801/87 and 19,802/87, and EP-A317262 and EP-A532337, the entire contents of each of which are incorporated herein by reference.

Hydrogenated polystyrene resin:

suitable hydrogenated polystyrene-based polymers may have a linear or star branched structure. Linear forms are described, for example, in JP-B7-114030, and polymers having a star-branched structure are described, for example, in WO 0148031.

For the substrate resin, mixtures of the above polymers may also be used. Suitable additives such as heat stabilizers, mold release agents, and the like, and fillers may also be added to the acrylic resin, the polystyrene resin, the polycycloolefin resin, and the hydrogenated polystyrene resin.

Binder material:

the binder material is typically a UV-curable and spin-coatable (coatable) resin, which may contain binders and reactive diluents and additives such as UV initiators or solvents. Typical photoinitiators (UV initiators) are alpha-hydroxyketones (Irgacure)Ciba)、(DarocurCiba) or acylphosphines (Darocur)Ciba)。

The binder may be selected from the following types, for example: urethane acrylates, for exampleXP2513、U 100、U 200、XP 2614 orVP LS 2220, Bayer MaterialScience AG or amine-modified polyether acrylates such asVP LS 2299, Bayer MaterialScience AG or elastomeric polyester acrylates such asLP WDJ 1602，Bayer MaterialScienceAG。

Urethane acrylates can be synthesized from (meth) acryloyl (acyloyl) containing alcohols and di-or polyisocyanates. Processes for synthesizing polyurethane acrylates are known and are described, for example, in DE-A-1644798, DE-A2115373 or DE-A-2737406. The (meth) acryloyl group containing alcohol may be an ester of acrylic or methacrylic acid with a di-functional alcohol (including a free hydroxyl group) such as 2-hydroxyethyl-, 2 or 3-hydroxypropyl or 2-, 3-, 4-hydroxybutyl- (meth) acrylate and mixtures thereof. Alcohols containing mono-functional (meth) -acryloyl groups may also be used or products consisting essentially of such alcohols obtained by esterification of n-functional alcohols with (meth) acrylic acid may also be used, whereby mixtures of different alcohols may also be used as alcohols, provided that n is an integer or mean value (average value) of more than 2 to 4, preferably 3, and whereby (n-1) moles of (meth) acrylic acid per mole of the above-mentioned alcohols are most preferred.

In addition, products of these alcohols containing a mono-functional (meth) acryloyl group with epsilon (epsilon) -caprolactone may be used. The products of hydroxyalkyl (meth) acrylic acids with epsilon (epsilon) -caprolactone are preferred.

For di-or polyisocyanates, in principle all (cyclo) aliphatic, aliphatic and aromatic structures are suitable, preferred (cyclo) aliphatic structures being, for example, hexamethylene-di-isocyanate or isophorone di-isocyanate, tri-methylhexa-methylene di-isocyanate, bis- (isocyanato) cyclohexyl) methane or their derivatives with polyurethane-isocyanurate-, allophanate-, biuret-, uretdione-structures, and mixtures thereof.

Suitable amine-modified polyether acrylates are known in principle and can be prepared by esterification of methacrylic acid with alcohols of 3 functional groups and mixtures thereof and subsequent reaction with primary amines. Among the alcohols or mixtures thereof are low molecular weight products such as alkoxylated o-glycerol or trimethylolpropane, for example the reaction product of ethylene oxide and trimethylolpropane (containing an OH value of 550mg KOH/g). Preferably, 0.7 to 0.9mol of (methacrylic) acid is used per mole of alcohol. For the subsequent reaction with primary amines, mono-alkylamines and hydroxyalkylamines are suitable, for example hydroxyethylamine. The amount of mono-alkylamine used corresponds to a molar ratio of mono-alkylamine to (meth) acrylic double bond of from 0.005: 1 to 0.4: 1, preferably from 0.01: 1 to 0.3: 1.

Suitable polyester acrylates are low-viscosity products which are synthesized in principle according to known azeotropic esterification methods. Particularly suitable are polyester acrylates consisting of alpha, beta-ethylene (ethylene) unsaturated carbonic acid, alkoxylated polyether triols, especially propoxylated triols and acrylic acid, whereby the ratio of OH-groups to carboxyl groups is preferably from 1,2 to 1, 6.

The reactive diluent may be selected from the following classes: ethoxylated alkyl acrylates such as 2- (2-ethoxyethoxy) ethyl acrylate (Sartomer SR)Sartomer) and t acrylic acid mono-functional esters such as ethoxylated phenyl acrylates such as ethoxylated (3) phenol monoacrylate (Photomer 4039)Cognis), alkyl acrylates such as lauryl-or stearyl-acrylate, cycloaliphatic acrylates such as isobornyl acrylate and heterocyclic acrylates such as tetrahydrofurfuryl acrylate.

A light transmitting layer:

the light transmitting layer is typically a UV-curable and spin-coatable resin having a real part of the refractive index of at least 1.41 measured at 405 nm. The resin may comprise binder and reactive diluent molecules and further additives such as UV initiators or solvents. Typical photoinitiators (UV initiators) are alpha-hydroxy ketones such as 1-hydroxy-cyclohexyl-phenyl-ketone(s) ((R))184, Ciba) or else 2-hydroxy-2-methyl-1-phenyl-1-propanone (Darocur)Ciba), or monoacylphosphines such as 2, 4, 6-trimethylbenzoyl-diphenyl-phosphine oxide (phosphinioxide) ((Ciba)TPO, Ciba). The binder molecules may be selected from, for example, urethane acrylates or polyether acrylates. The reactive diluent may be selected from the group consisting of ethoxylated alkyl acrylates, ethoxylated phenyl acrylates, cycloaliphatic acrylates and heterocyclic acrylates.

Light transmitting layer as high refractive index layer coating a (hri):

the high refractive index light-transmitting layer (coating A) may be prepared from a casting solution A^*Obtaining a casting solution A^*Applied to the substrate (S) or applied to the information and recording layer (B) and crosslinked.

Component A^*(casting solution)

Casting solution A according to an embodiment of the present invention^*Comprises the following components:

a1: comprising nanoparticles and a suspension of a mixture of water and at least one organic solvent,

a2: adhesive agent

And optionally

A3: other additives.

As used herein, nanoparticles are understood to have an average particle size (d)₅₀) Particles of less than 100nm, preferably from 0.5 to 50nm, particularly preferably from 1 to 40nm, very particularly preferably from 5 to 30 nm. Preferred nanoparticles additionally have a d of less than 200nm, in particular less than 100nm, particularly preferably less than 40nm, very particularly preferably less than 30nm₉₀The value is obtained. The nanoparticles are preferably in the form of a single particleThe dispersed (monodisperse) form is present in suspension. Average particle size d₅₀Is in each case 50 wt.% of the particle size in the range above and below this diameter. D₉₀The particle size of the particles with a value of 90 wt.% is below this diameter. Laser scattering or, preferably, the use of Analytical Ultracentrifugation (AUC) will be appropriate for determining particle size and confirming monodispersity. AUC is known to those skilled in the art, as described in "Particle Characterization", part.part.syst. charact, 1995, 12, 148-.

To prepare ingredient A1 (suspension containing nanoparticles and a mixture of water and at least one organic solvent), A1₂O₃、ZrO₂、ZnO、Y₂O₃、SnO₂、SiO₂、CeO₂、Ta₂O₅、Si₃N₄、Nb₂O₅、NbO₂、HfO₂Or TiO₂Is suitable, CeO₂Aqueous suspensions of nanoparticles are particularly suitable. Particularly preferably, the aqueous suspension of nanoparticles comprises one or more acids, preferably carboxylic acids rc (o) OH, wherein R ═ H; c₁To C₁₈-alkyl, which may be optionally substituted by halogen, preferably by chlorine and/or bromine; or C₅-to C₆-cycloalkyl, C₆-to C₂₀-aryl or C₇-to C₁₂Aralkyl, each of which may optionally be substituted by C₁To C₄Alkyl and/or halogen (preferably chlorine, bromine). R is preferably methyl, ethyl, propyl or phenyl and particularly preferably ethyl. The nanoparticle suspension may also contain as an acid an inorganic acid, such as nitric acid, hydrochloric acid or sulfuric acid. The aqueous suspension of nanoparticles preferably contains 0.5 to 10 parts by weight, particularly preferably 1 to 5 parts by weight, of acid, based on the total parts by weight of acid and water. For example, nanoparticle suspensions available from Nyacol NanoTechn, Inc., USACeO₂ACT (CeO obtained with acetic acid)₂Aqueous suspensions of nanoparticles, pH 3.0) and CeO₂-NIT (CeO obtained with nitric acid)₂Aqueous suspensions of nanoparticles, pH 1.5) are suitable.

Part of the water from these aqueous suspensions is replaced by at least one organic solvent. This exchange of partial solvent is carried out by distillation or by diafiltration, preferably by ultrafiltration, for example according to the "cross-flow" method. Cross-flow ultrafiltration is a form of industrial scale ultrafiltration (M.Mulder: Basic Principles of Membrane Technology, KluwerAcad. publ., 1996, 1 st edition) in which the solution to be filtered (feed solution) flows tangentially across the Membrane. This solvent exchange preferably uses at least one solvent selected from the group consisting of alcohols, ketones, diketones, cyclic ethers, diols, glycol ethers, glycol esters, N-methylpyrrolidone, dimethylformamide, dimethyl sulfoxide, dimethylacetamide and propylene carbonate. Preference is given to using a solvent mixture of at least two solvents selected from the abovementioned classes of solvents, particular preference being given to using a solvent mixture of 1-methoxy-2-propanol and diacetone alcohol. Particular preference is given to using a solvent mixture of 1-methoxy-2-propanol (MOP) and diacetone alcohol (DAA), preferably in a ratio of from 95: 5 to 30: 70, particularly preferably from 90: 10 to 50: 50. Water may be present in the solvent, preferably in an amount of up to 20 wt.%, more preferably in an amount of 5-15 wt.%.

In a further embodiment of the invention, the suspension of nanoparticles may be prepared by solvent exchange in at least one of the above-mentioned organic solvents, followed by the addition of an additional solvent selected from the group consisting of alcohols, ketones, diketones, cyclic ethers, such as tetrahydrofuran or dioxane, glycols, glycol ethers, glycol esters, N-methylpyrrolidone, dimethylformamide, dimethyl sulfoxide, dimethylacetamide, solketal, propylene carbonate and alkyl acetates, such as butyl acetate, in which embodiment water may be present in the solvent, preferably in an amount of up to 20 wt.%, more preferably in an amount of 5-15 wt.%.

A preferred option given is the use of ultrafiltration membranes made from polyether polysulfones, which preferably have a cut-off value (cut-off) of less than 200,000D, preferably less than 150,000D, particularly preferably less than 100,000D. The cut-off values of the films are defined as follows: molecules of the corresponding size (e.g., 200,000D and larger) are retained, while molecules and smaller sized particles are able to pass ("BasicPrincples of Membrane Technology", M.Mulder, Kluwer academic publishers, 1996, 1 st edition). Such ultrafiltration membranes retain nanoparticles even when the solvent is passed through at high flow rates. According to the invention, the solvent exchange takes place by continuous filtration, the water passing through being replaced by a corresponding amount of solvent or solvent mixture. As an alternative to polymer membranes, ceramic membranes may also be used in the steps of the solvent exchange process.

The process according to this embodiment of the invention is characterized in that the replacement of water by one of the abovementioned organic solvents or solvent mixtures does not fall below the limit value of 5 wt.% in the resulting nanoparticle suspension (component A1). Preferably, the replacement of water by the organic solvent or solvent mixture should be carried out such that the resulting nanoparticle suspension (component a1) has a water content of 5 to 50 wt.%, preferably 7 to 30 wt.%, particularly preferably 10 to 20 wt.%. The resulting nanoparticle suspension preferably contains 1-50 wt.%, more preferably 5-40 wt.%, and particularly preferably 15-35 wt.% nanoparticles (hereinafter referred to as the nanoparticle solid fraction).

If the solvent exchange of the nanoparticle suspension on the membrane cell is carried out for a long time, thus resulting in a water content of less than 5 wt.%, particle aggregation occurs, so that the resulting coating cannot satisfy the conditions of monodispersity and high transparency. On the other hand, if the water content in the organic-based nanoparticle suspension is greater than 50 wt.%, the binder to be used in the subsequent step may no longer be soluble in the aqueous suspension to give a clear solution, so that in both cases, that is to say, the aggregated nanoparticles or the binder cannot be dissolved to give a clear solution, the resulting coating cannot meet the requirements for both a high refractive index n and a high transparency.

As binders (component A2), it is possible to use non-reactive heat-drying thermoplastics, for example polymethyl methacrylate (A) ((A))Tennants) or polyvinyl acetate (Mowilith)Synthomer), and reactive monomer components that can yield a highly crosslinked polymer matrix after coating, either by chemical reaction or by photochemical reaction. For example, crosslinking is carried out by UV radiation. Crosslinking by UV radiation is particularly preferred in view of increased scratch resistance. The active ingredient is preferably a UV-crosslinkable acrylate system as described above, for example as described in P.G.Garrtat"1996, C.Vincentz VIg., Hannover. The binder (component a2) is preferably selected from at least one of polyvinyl acetate, polymethyl methacrylate, polyurethane and acrylate. The binder (component a2) is particularly preferably at least one selected from the group consisting of hexanediol diacrylate (HDDA), tripropylene glycol diacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate (DPHA), ditrimethylolpropane tetraacrylate (DTMPTTA), tris- (2-hydroxyethyl) -isocyanurate triacrylate, pentaerythritol triacrylate, tris- (2-hydroxyethyl) -isocyanurate triacrylate and hexanediol diacrylate (HDDA).

The component used as an additional additive (component a3) in the casting solution is preferably at least one additive selected from the group consisting of photoinitiators and thermal initiators (initiators). The additive (component A3) is used in an amount of up to 3 parts by weight, preferably from 0.05 to 1 part by weight, particularly preferably from 0.1 to 0.5 part by weight, based on the total parts by weight of the components of the casting solution. Typical photoinitiators (UV initiators) are alpha-hydroxyketones (A-H184, Ciba) or monoacylphosphines (TPO, Ciba). The amount of energy (energy of UV radiation) required to initiate UV polymerization is in the range of about 0.5 to 4J/cm²Particularly preferably 2.0 to 3.0J/cm²Within the confines of the coated surface. As additional additives, BYK, e.g. BYR, is known under the trade name BYK/Altana (46483Wesel, Germany)So-called coating additives, which are supplied, are also suitable.

Casting solution a for high refractive index coating according to an embodiment of the present invention^*Can be prepared by dissolving at least one binder (component A2) and optionally additional additives (component A3) in an organic solvent or solvent mixture which may contain water. The resulting solution (hereinafter referred to as binder solution) was mixed with component a1 and optionally filtered and degassed. In a preferred embodiment, component a1 contains the same organic solvent or solvent mixture as the binder solution.

Casting solution A^*Preferably having the following composition:

12 to 30 parts by weight, preferably 13 to 25 parts by weight, particularly preferably 14 to 19 parts by weight, of the nanoparticulate solid fraction,

2 to 8 parts by weight, preferably 2.5 to 5 parts by weight, of a binder

0 to 3 parts by weight, preferably 0.05 to 1 part by weight, particularly preferably 0.1 to 5 parts by weight, of an additional additive (component A3),

7 to 28 parts by weight, preferably 15 to 27 parts by weight, particularly preferably 20 to 26 parts by weight of water and water

32 to 79 parts by weight, preferably 42 to 70 parts by weight, particularly preferably 50 to 63 parts by weight, of an organic solvent,

the sum of the parts by weight of the components is normalized to 100.

Casting solution A^*Usually having solids of 10-50 wt.%, preferably 14-28 wt.%And (4) content. Casting solution A^*Is the sum of the components A2, A3 and the solid portion of the nanoparticles. The ratio of binder (component A2) to the nanoparticle solid fraction in the casting solution is preferably from 40: 60 to 7: 93, particularly preferably from 26: 74 to 12: 88.

The layer thickness of the coating A can generally be from 1nm to 3000nm, preferably from 200nm to 2000nm, particularly preferably from 500nm to 1500 nm. The layer thickness can be set by the solids content of the casting solution, in particular in the case of spin coating methods. If a high layer thickness of the coating is desired, a high solids casting solution is used; if a thinner coating is desired, a low solids casting solution is used.

The properties of coating a of the coated product were determined as follows: the real and imaginary parts n, k of the complex index are measured at a wavelength of 400-410nm, i.e. in the blue laser wavelength range. Surface roughness R measured by AFM (atomic force microscopy)_aThe value is obtained. To determine the scratch resistance, a diamond needle having a tip radius of 50 μm was moved over the coating under the application of 40g of gravity at a forward speed of 1.5cm/s, and the depth of the scratch produced was determined. Details of the various assay methods are given in the section on the production and testing of coated products.

A substrate S:

the base sheet (S) includes a disc-shaped article made from the above-described polymer resin and prepared by the method described below. An optical recording medium is formed by sequentially applying at least one recording layer and one light-transmitting layer to a substrate.

A method of producing a substrate for an optical recording medium:

to produce a substrate for an optical recording medium from the above resin, an optical disc substrate can be formed by injection molding using an injection molding machine (including an injection compression molding machine) equipped with a master stamper having pits and grooves that satisfy the technical conditions required for an optical recording medium and a precise surface. The thickness of the optical disc substrate may be 0.3-2.0 mm. Such an injection molding machine may be a commonly used machine, but is preferably a machine made of a cylinder and a screw having a material with corrosion resistance and abrasion resistance, which is low in adhesion to a resin, in order to suppress generation of carbides and improve reliability of the optical disk substrate. For the purposes of the present invention, the environment of the compression molding step is preferably as clean as possible. It is important that the material to be molded should be completely dried to remove water and that moisture retention that could cause decomposition of the molten resin be avoided.

The resin used for the optical disk substrate of the present invention preferably has sufficiently high fluidity, which is advantageous for transferability (transferability) during injection molding or injection compression molding.

The optical recording medium can be produced by forming at least one reflective film on at least one side of the substrate of the present invention. The material of the reflecting film is element metal or composite metal. Al or Au may be used alone, or an Al alloy containing Ti in an amount of 0.5 to 10 wt%, preferably 3.0 to 10 wt%, or an Al alloy containing Cr in an amount of 0.5 to 10 wt% is preferably used. The reflective film may be formed by physical vapor deposition, ion beam sputtering, DC sputtering, or RF sputtering (high-frequency sputtering). Only such a metal thin film (reflective layer) is sufficient for the optical recording medium of the present invention to be recorded in advance, but in addition to the reflective layer, a recording layer (e.g., a phase change film and a dye in the case of a rewritable or recordable and recordable optical recording medium, and a magneto-optical recording film in the case of a permanent magnet-optical recording medium) and a light transmitting layer may be formed to obtain a rewritable or recordable optical recording medium of the present invention.

The phase-change thin film recording material layer is made of chalcogen alone or a chalcogenide compound. In particular, Te, Se or chalcogenide-based materials such as Ge-Sb-Te, Ge-Te, In-Sb-Te, In-Se-Te-Ag, In-Se-Tl-Co, In-Sb-Se, Bi can be used₂Te₃、BiSe、Sb₂Se₃Or Sb₂Te₃。

A longitudinally magnetized film having permanent magnet-optical characteristics including a peltier effect or a faraday effect, for example, an amorphous alloy film of Tb-Fe-Co, is used as the permanent magnet-optical recording film layer.

The light-transmitting layer is formed on the recording layer. The light-transmitting layer is made of a material that transmits laser light and is described in more detail in the section of the general description of the light-transmitting layer and in the section of the general description of casting (catching) as the light-transmitting layer of the high refractive index layer (HRI).

The method for forming a light-transmitting layer is described in more detail in the section of the method for producing a light-transmitting layer and the method for producing a light-transmitting layer as a high refractive index layer. Further, the thickness of the light-transmitting layer is limited to 1nm to 3000nm, preferably 200nm to 2000nm, and particularly preferably 500nm to 1500nm, in order to eliminate spherical aberration and chromatic aberration.

The basic composition of the optical recording medium of the present invention has been described above. A dielectric layer may be added to the above composition to control optical characteristics and thermal properties of the optical recording medium, and in this case, a light reflective layer, a first dielectric layer, a recording layer, a second dielectric layer, and a light transmissive layer may be formed on a substrate in the above order. Further, the above-mentioned optical recording medium of the present invention is not limited to only one superimposed layer on the substrate, and may include the above-mentioned different layers. It should also have a plurality of superimposed layers, each separated by a spacer layer made of a material that can also be used for the light-transmitting layer.

One-component injection molding method (1-K molding):

hereinafter, the preparation of a standard 1-K molded substrate suitable for an optical recording medium according to an embodiment of the present invention is described, which is used in the experimental part and does not limit the scope of the present invention as long as the substrate satisfies the requirements of young's modulus E and quality factor. An optical disk substrate having a diameter of 120mm and a thickness of 1.2mm was prepared from each pellet by injection molding using Arburg Alldish equipped with a model AWM2313 and a DVD-ROM master stamper. Or an Arburg 370U 70030/302-K injection molding machine equipped with a sandwich plate, Philips CD-Mould and DVD-ROM master stamper press was used. For this purpose, the mould is modified in such a way that it is suitable for sandwich plates. For a 1-K molded substrate, the machine was fed with pellets of the same resin.

To form each optical recording medium, a reflective layer (100nm Ag) was formed on a 1-K molded substrate by physical vapor deposition (Leybold Al 100) or by DC sputtering (Reuter LP 800). According to the above method, the reflective layer and the light-transmitting layer of the HRI type are formed thereon.

To form a test arm for measuring young's modulus E and quality factor Q according to ASTM E756-05, the arm can be cut into individual substrates of optical recording media or substrates covered with a recording overlay and a light transmitting layer, or the test arm from the corresponding resin used for the substrate of the present invention can be injection molded directly 1-K.

Two component sandwich injection molding method (2-K molding):

hereinafter, the preparation of a standard 2-K interlayer molding substrate suitable for an optical recording medium according to an embodiment of the present invention is described, which is used in the experimental part and does not limit the scope of the present invention if the substrate satisfies the requirements of young's modulus E and quality factor. An optical disk substrate having a diameter of 120mm and a thickness of 1.2mm was injection molded from each pellet using an Arburg 370U 70030/302-K injection molding machine equipped with a sandwich flat plate, Philips CD-Mould and DVD-ROM master stamper. For this purpose, the mould is modified in such a way that it is suitable for sandwich plates. For a 2-K sandwich molded substrate, the machine is supplied with pellets of different resins that will form a three-layer sandwich substrate, i.e., a core layer made of one resin and two skin layers made of the other resin. The ratio of core layer thickness to skin layer thickness is primarily controlled by the relative amounts of the feedstock dispensed. In the first shot (shot), the skin resin is injected into the cavity of the mold, in the second shot, the core layer is injected into the cavity of the mold, and in the third shot, the gate is sealed with the skin material. To obtain a uniform core layer thickness, the resin and the treatment temperature are preferably selected in such a way that the resin having higher fluidity forms the skin layer.

To form the corresponding optical recording medium and cut out (cut out) a test arm for young's modulus E and quality factor Q measurement, the same method as described in the single component injection molding method (1-K molding) was employed except for direct 1-K injection molding of the test arm.

UV-bonding method (UV bonding):

hereinafter, the preparation of a standard UV-adhesive substrate suitable for an optical recording medium according to an embodiment of the present invention is described, which is used in the experimental section and does not limit the scope of the present invention if the substrate satisfies the requirements of young's modulus E and quality factor. Discs with a diameter of 120mm and a thickness of 0.6mm were injection molded from each pellet using a Sinkulus E Mould DVD-R machine with a Sinkulus in-line (Streamline) IIDVD-R attached (equipped with ST-molds from Axxicon molds and DVD + R or DVD-R master stamper). UV-bonded substrates were produced from two 0.6mm thick discs by a process downstream of the flow line IIDVD-R of Singauus above using deactivated dye dispersions and deactivated metallization, but activating UV-bonding. For this purpose, the UV-adhesive material was fed to a Sinkulus's flow line II DVD-R adhesive tank. The UV adhesive was distributed on a spin stand (spin stand) and UV curing was performed using the following settings to achieve the specified adhesive layer thickness:

thickness of adhesive layer: about 90 μm to about 40 μm

Rotation speed 1: 1800RPM 4500RPM

Rotation speed 2: 2600RPM 6500RPM

Amount of binder: 1.2gr 0.6gr

Irradiation time: 1.5sec 0.9sec

The base power: 1.8kW and 1.8kW

Maximum power: 4.0kW and 4.0kW

Tank temperature: 34 ℃ at 34 DEG C

Needle temperature: 34 ℃ at 34 DEG C

Alternatively, the UV-bonded substrate can be produced from two 0.6mm thick discs using a laboratory spin coater (Karl SussCT62), one 0.6mm disc being clamped to the coater, and the UV-bonding material being coated at a low rotation speed of 200RPM through the inner circumference of the already clamped optical disc. A second 0.6mm disc was placed on the first clamped disc and the UV bonding material was spread between the two discs by spinning the spin coater at 1500RPM for 8 seconds.

To form the corresponding optical recording medium and cut (cut out) into test arms for young's modulus E and quality factor Q measurement, the same method as described in the single component injection molding method (1-K molding) was employed except for direct 1-K injection molding of the test arms.

Method for producing a light transmitting layer:

by spin coating, the resin may be applied to the surface of the substrate or the surface of the information and recording layer. Subsequent crosslinking of the resin may be carried out on a UV exposure apparatus, for example: for this purpose, the coated substrate is placed on a conveyor belt and moved past a UV light source (Hg lamp, 80W) at a speed of approximately 1 m/min. The process can also be repeated to affect each m²Of the radiation energy of (1). At least 1J/cm²Preferably 2 to 10J/cm²The radiation dose of (2) is preferred. The coated substrate may then be subjected to a thermal post-treatment, preferably with hot air at a temperature of 60 ℃ to 120 ℃, for example for 5 to 30 minutes.

Method for producing a light-transmitting layer as a high refractive index layer (HRI):

coating (a) can be prepared as follows:

i) replacing a portion of the water contained in the aqueous nanoparticle suspension with at least one organic solvent, so that the resulting nanoparticle suspension (component A1) has a water content of 5-50 wt.%,

ii) adding at least one binder (component A2) to the nanoparticle suspension (component A1) to obtain a casting solution (A)^*)，

iii) casting the solution (A)^*) Applied to the substrate (S) or the information and recording layer (B), and

iv) crosslinking the casting solution (A) by thermal or photochemical means^*)。

Preferably, after step iii), from the casting solution (A)^*) The coated substrate (S) is completely or partially freed of residual solvent and/or a thermal post-treatment is applied to the coating obtained after step iv).

Casting solution A^*Optionally sonicated for up to 5 minutes, preferably 10-60 seconds, and/or filtered through a filter, preferably a 0.2 μm membrane (e.g., RC membrane, Sartorius). Sonication can be applied to break down nanoparticle agglomerates (if present).

The casting solution may be applied to the surface of the substrate or the surface of the information and recording layer. After the excess casting solution is removed, preferably by spinning, a residue of the casting solution remains on the substrate, the thickness of which depends on the solids content of the casting solution and, in the case of spin coating, on the spinning conditions. Part or all of the solvent contained in the casting solution may optionally be removed, preferably by heat treatment. The subsequent crosslinking of the casting solution or the residue is carried out by thermal methods (for example using hot air) or photochemical methods (for example UV light). Photochemical crosslinking may be performed on a UV exposure apparatus, for example: for this purpose, the coated substrate is placed on a conveyor belt and moved past a UV light source (Hg lamp, 80W) at a speed of approximately 1 m/min. The process can also be repeated to affect each m²Of the radiation energy of (1). At least 1J/cm²Preferably 2 to 10J/cm²The radiation dose of (2) is preferred. The coated substrate may then be subjected to a thermal post-treatment, preferably with hot air at a temperature of 60 ℃ to 120 ℃, for example 5 to 30 minutes.

The invention therefore also provides a method of producing a light transmitting layer, and comprising the steps of:

i) preparing a suspension of monodisperse nanoparticles in at least one organic solvent, starting from the aqueous nanoparticle suspension, removing the water present in the aqueous nanoparticle suspension and simultaneously replacing it with at least one organic solvent, so that the nanoparticle suspension has a water content of from 5 to 50 wt.%,

ii) adding at least one binder (component A2) and optionally additional additives (component A3) to the nanoparticle suspension (component A1) to obtain a casting solution (A)^*)，

iii) applying the casting solution from ii) to the substrate or the information and recording layer (B),

iv) optionally removing part or all of the solvent contained in the casting solution, preferably by heat treatment, to obtain a residue on the substrate,

v) crosslinking the casting solution or residue by thermal or photochemical means, and

vi) optionally heat treating the coating, preferably at 60-120 ℃.

Description of the test procedure:

1. determination of Young's modulus E and quality factor Q

To determine the Young's modulus E and damping related factor Q (quality factor) of the material in the frequency range of about 10Hz-10KHz, a setup similar to that described in ASTM E756-05 (FIG. 1) was used. The measuring principle is based on the resonance frequency f of the rocker arm (oscillating beam) of the material concerned_nEvaluation of (3). To excite the resonance frequency, the arm is fixed to one side of a piezoelectric oscillator (Piezo-shaker), which is driven by an analog white noise signal extending from 1mHz to 10 KHz. The response of the arm to the excitation (appearance), e.g. the velocity, is recorded relative to the frequency measured with a Laser-Doppler-Vibrometer (LDV) at the arm tip not fixed to the piezoelectric oscillator, e.g. the normalization (normalized) of the velocity relative to the frequency of the excitation at the arm tip fixed to the piezoelectric oscillator. From this reaction curve, E and Q were calculated as follows:

equation 1

Equation 2

Wherein

E-young's modulus (Pa) of the arm material,

f_nthe resonance frequency (Hz) for the modulus n,

Δf_nfull bandwidth (FWHM) Hz at half power of the modulus n,

C_ncoefficient of modulus n for clamped-free vibrating (uniform) arms,

h-the thickness of the arm in the direction of oscillation (meters),

l is the length of the arm (meters),

n-modulus: 1,2,3,

q-the quality factor of the arm material, dimensionless,

ρ is the mass density of the arm (kg/m)³)

For example, the arms may be cut into discs, which may be manufactured according to the above-described procedure or may be injection molded. This description should not limit how the arm is made, at least the layer structure appears to be the same in the direction of the arm thickness. The arm width W is chosen to be 0.013m and the length l is chosen such that the resonance frequency fits wellThe measured frequency range is 10Hz-10 kHz. At the moment of measurement f_nLess than 2000Hz and measured f_n+1Above 2000Hz, the values of E and Q at 2000Hz were calculated by linear interpolation using the respective values derived from equations 1 and 2.

2. Measurement of Pit (Pit) height using AFM

The pit height was determined by atomic force microscopy in tapping mode.

3. Surface roughness by AFM measurement

Surface roughness is given as R_aMeasured in Tapping Mode (Tapping Mode) by atomic force microscopy according to ASTM E-42.14 STM/AFM.

4. Mass density

The mass density p was measured on samples cut into discs using a Mettler density kit (Mettler density kit) Mettler AT 250H66765 AT room temperature using ethanol as the immersion liquid, or the discs were cut into rectangular discs of known width W, known height H and known length 1. The mass m of the rectangular disk is determined by weighing with a balance (e.g. Mettler AT 250) and ρ is calculated by ρ ═ m/(l · H · W).

5. Measurement of adhesive thickness

Thickness d of the two halves of the disk₁And d₂Measured in a DVD substrate model using a Schenk Prometheus 140 off-line scanner. Total thickness d of the bonded discs_tMeasured in a CD substrate model using a Schenk Prometheus 140 off-line scanner. Thickness d of the adhesive_BFrom these thicknesses, the following is calculated:

d_B＝d_t-(d₁+d₂) Equation 3

6. Thickness d of the core layer_CAnd the thickness d of the skin layer_S1And d_S2The determination of (1):

thickness d of two skin layers_S1And d_S2And the thickness dc of the core layer is determined by stereomicroscope on an ultrathin section of the cross section of the disc.

7. Tilt measurement

The tilt angle (tilt) of the disc was measured with a Schenk Prometheus 140 offline scanner.

8. Measurement of complex refractive index n^*＝n+ik

Complex refractive index n of the coating^*The real number part n of (a) and the imaginary number part k of the complex refractive index (hereinafter also referred to as absorption constant k) are obtained from the emission spectrum and the reflection spectrum thereof. To obtain these spectra, a coating film about 100-300nm thick was applied via spin coating from a dilute solution onto a quartz glass support. The emission and reflection spectra of this layer structure are determined by means of a spectrometer from STEAGETA-Optik, CD-determination System (Measurement System) ETA-RT, and the layer thicknesses of the coating and the spectral dependencies of n and k are then suitable for determining the emission and reflection spectra. Fitting was performed using the internal software of a spectrometer that required the spectral dependence of n and k of the quartz glass substrate, which had been determined in previous blank measurements, k being related to the decay constant α of the light intensity as follows:

equation 4

λ is the wavelength of the light.

9. Measurement of scratch resistance

To determine the scratch resistance of the coating on the disk substrate, scratches were made radially from the inside to the outside on the coated substrate using a diamond needle having a tip radius of 50 μm, at a feed speed of 1.5cm/s and applying a weight of 40 g. Scratch depth was measured using an AlphaStep 500 step profiler (profiler) from Tencor. This scratch depth is taken as a measure of scratch resistance. A small depth value of the scratch means a high scratch resistance of the corresponding coating.

10. Determination of the Water content of the coating solution

The water content of the coating solution was determined by the Karl Fischer method.

11. Determination of the thickness of the light-transmitting layer

For the thickness range of 1nm to 1500nm, the light transmitting layer is applied to a transparent BPA-polycarbonate CD-substrate, which is molded with a blank master stamper (without pits and grooves) using the same method as that for applying the light transmitting layer to the substrate of the optical recording medium of the present invention. The emission and reflection spectra of the layer structure are determined by means of a spectrometer from STEAG ETA-Optik, CD-measuring System (Measurement System) ETA-RT, the layer thickness of the coating being adapted to the measured emission and reflection spectra. The fitting was performed using the internal software of a spectrometer that required the spectral dependence of n and k of the polycarbonate substrate, which had been determined in previous blank measurements, while n and k of the light transmitting layer were based on the complex refractive index n^*Description of the assay of n + ik. The thickness of the light-transmitting layer which has been applied to the substrate of the optical recording medium is measured by a CD-measuring system ETA-RT with the die "ETA-DVR measuring system for blue-ray/Digital Video Recording (DVR) optical discs" for the thickness range of 1500nm to 150000 nm. For this purpose, the real part n of the complex refractive index of the light-transmitting layer is necessary, which depends on the complex refractive index n^*As described in the measurement of n + ik.

The invention will now be described in more detail with reference to the following non-limiting examples.

Examples

A reflective layer (B) of 100nm Ag (if applied) is formed on the substrate (S) by DC sputtering (Reuter LP 800).

A light-transmitting layer, if applied on a reflective layer on a substrate (S), obtained by the following composition and procedure:

component A.0

Cerium oxide CeO₂-CeO₂Aqueous suspension of (a): 20 wt.% CeO₂Nanoparticles in 77 wt.% water and 3 wt.% acetic acid, pH of the suspension: 3.0, suspended CeO₂Particle size of nanoparticles: 10-20nm, specific gravity (spec, weight): 1.22g/ml, viscosity: 10 mPas, manufacturer: nyacol inc., Ashland, MA, USA.

Component A.2-1

Adhesive: dipentaerythritol penta/hexa-acrylate (DPHA, Aldrich).

Component A.2-2

Adhesive: hexanediol diacrylate (HDDA, Aldrich).

Component A.3

UV photoinitiator:184 (1-hydroxy-cyclohexyl phenyl ketone), ciba specialty Chemicals inc., Basel, switzerland.

The following ingredients were used as organic solvents in the examples:

1-methoxy-2-propanol (MOP), manufacturer: aldrich

Diacetone alcohol (DAA), manufacturer: aldrich.

CeO was subjected to cross-flow ultrafiltration as described below₂The aqueous suspension of nanoparticles (component a.0) is converted into a suspension of nanoparticles containing water and MOP (component a.1).

Membrane modules from PALL (centrifugal OS070C12) with UF membrane cassettes (PES, MW 100,000) were used for cross-flow Ultrafiltration (UF). The permeation is performed at a pressure of 2.5 bar, the aqueous permeate is discarded and the reduced retentate is replaced with the alcoholic solvent 1-methoxy-2-propanol (MOP). 6.5 l of component A.0 are used. As shown in the table below, the filtration was terminated after 3 cycles of different duration and a suspension of nanoparticles in a mixture of organic solvent MOP and water was thus obtained (component a.1).

Table 1: composition and Properties of component A.1

Composition (I)	Penetration time [ h: min]	Amount of permeate [ liter ]]	Water content of retentate1)[wt.％]	Solids content [ wt.%]
					A.1	15:45	13.2	12.3	30.4

1) Measured by Karl Fischer titration

2) Containing 3 wt.% acetic acid

Casting solution with a water content of 10 wt.% (component A)^*) By mixing solution A and solution BObtaining:

solution A: 25g of component A.2-1 and 6.2g of component A.2-2 are dissolved with stirring in 108g of solvent DAA. Then 2.35g of component A.3 are added, whereupon a clear solution is formed.

Solution B: in a glass flask, 54g of solvent DAA are added to 435g of component a.1 and the mixture is stirred, whereupon a clear, yellow suspension is obtained, which is sonicated for 30 seconds. During this time 32.5g of water were added.

Solutions A and B were combined, then sonicated for 30 seconds and filtered through a 0.2 μm filter (Minisart RC membrane). The casting solution (component A) was calculated as follows^*) The components of (A):

table 2: casting solution component A^*Composition and characteristics of

	Composition wt. -%)
		Component A.2-1DPHA	3.77
Component A.2-2HDDA	0.94
		Component A.3	0.35
CeO2 1)	19.94
		MOP	20.27
DAA	44.70
		Water (W)	10.02
Solids content [ wt.%]2)	25.0

1) The solid part of the nanoparticles (here CeO) resulting from component A.1₂)

2) The indicated solids content of the respective casting solutions is the component A.2-1+ component A.2-2+ component A.3+ nanoparticle solid fraction (CeO)₂) The sum of (a) and (b).

The real part n of the complex index is 1.84 as measured at 405nm and the imaginary part k of the complex index is 0.004 as measured at 405 nm.

To coat the solution (component A)^*) Applying the component A on a reflective layer (B) on a disc-shaped substrate (S)^*By spin coating, component A^*Composition A was applied to the inside diameter of the clamped substrate from sringe at low speed 240RPM for a period of 2.1 seconds^*The distribution of component A was adjusted at 750RPM over a period of 3.5 seconds over the total area of the disk, at 10RPM over a period of 40 seconds^*Excess component A was removed by spinning at a high spin speed of 3000RPM for 40 seconds^*. Using mercury lamps at 5.5J/cm²The coating is crosslinked. The thickness of the residue layer of the light-transmitting layer was 730 nm.

Comparative example 1

According to a method of injection molding in a single componentMethod (1-K Molding), method described in the preparation of a standard 1-K molded substrate for optical recording media according to the invention, a disk having a diameter of 120mm and a thickness of 1.2mm was made of bisphenol A polycarbonate (BPA-PC, relative solution viscosity 1.202) Makrolon ODMolded in an Arburg Alldisc injection molding machine equipped with a model AWM2313 and a DVD-ROM master stamper. To form test arms (test beams) for determining young's modulus E and quality factor Q according to ASTM E756-05, the arms were cut into individual discs having a length l of 114mm, a thickness H of 1.2mm and a width W of 12.7 mm. The mass density, determined by a Mettler Density kit Mettler AT 250H66765, was 1.190g/cm³. The young's modulus E and quality factor Q were then measured at 2000Hz as E-2.53 GPa and Q-167.

Comparative example 2

According to the method described in the preparation of a standard 1-K molding substrate for optical recording media of the invention according to the one-component injection molding method (1-K molding), a 1.64mm thick test arm having a width W of 13.1mm and a length l of 81mm is directly injection molded from polystyrene (CAS-No.298-07-7, molecular weight 140000 Dalton, Aldrich/Germany) on an Arburg370 injection molding machine. The mass density, as determined by the Mettler Density kit Mettler AT 250H66765, was 1.014g/cm³. The young's modulus E and the quality factor Q were then measured at 2000Hz as E-3.28 GPa and Q-175 according to astm E756-05.

Comparative example 3

According to the method described in the preparation of a standard 1-K molding substrate for optical recording media of the invention, a 1.64mm thick test arm having a width W of 13.1mm and a length l of 81mm was injection molded directly from a polycarbonate compound (compound 4) made from bisphenol A having a solution viscosity of 1,202 and 20 wt-% carbon fibers (carbon fiber Tenax-U Type 234, Toho Tenax Europe GmbHWupportal Germany) on an Arburg370 injection molding machine according to the single component injection molding method (1-K molding). Mass Density through Mettler Density kit MettlerAT 250H66765 measurement 1.206g/cm³. The young's modulus E and quality factor Q were then measured as E ═ 6.18GPa and Q ═ 170 at 2000Hz according to ASTM E756-05.

Example 1 (substrate)

The compound (compound 1) was prepared from 79,95 wt.% BPA-polycarbonate (Makrolon OD) having a solution viscosity of 1.202Bayer MaterialScience), 5 wt.% Polymethylmethacrylate (PMMA)Degussa), 15 wt.% talc (Finntalc)Mondo Minerals, Helsinki/Finland) and 0,05 wt.% glycerol monostearate (Dimodan, Danisco/Germany) by mixing the components on a ZSK 25/4 extruder (Coperion HoldingGmbH, Stuttgart/Germany) and granulating the molten extrudate strands (strands) after cooling in a water bath. These pellets were molded in a 1-K injection molding process in a single component injection molding process (1-K molding) into disks of 120mm diameter and 1.2mm thickness as described above using an Arburg 370U 70030/302-K injection molder equipped with a sandwich plate, Philips CD-Mould and DVD-ROM master stamper. Test arms were prepared from the disk substrate as described in the single component injection molding method (1-K molding). The measured young's modulus E and quality factor Q are described in table 3.

Example 2 (optical recording medium)

The reflective and light transmissive layers described above were applied to the disk substrate of example 1. The scratch depth was determined to be 0.638 μm and the surface roughness was determined to be R_aTest arms were prepared from the disk substrate as described in the single component injection molding method (1-K molding). The measured young's modulus E and quality factor Q are described in table 3.

Example 3 (substrate)

Compound (Compound 2) was prepared from 59.90 wt.% BPA-polycarbonate (Makrolon OD)Bayer MaterialScience), 10 wt.% Polymethylmethacrylate (PMMA)Degussa), 30 wt.% talc (Finntalc)Mondo Minerals, Helsinki/Finland), 0.05 wt.% bis (2-ethylhexyl) phosphate (CAS-No.298-07-7, Alfa Aesar GmbH)&Co KG, Karlsruhe/germany) and 0.05 wt.% glycerol monostearate (Dimodan, Danisco/germany) were prepared by mixing the ingredients in a ZSK 25/4 extruder (Coperion HoldingGmbH, Stuttgart/germany) and granulating the molten extruded strands (strands) after cooling in a water bath. These pellets were molded in a 1-K injection molding process in a single component injection molding process (1-K molding) into disks of 120mm diameter and 1.2mm thickness as described above using an Arburg 370U 70030/302-K injection molder equipped with a sandwich plate, Philips CD-Mould and DVD-ROM master stamper. Test arms were prepared from the disk substrate as described in the single component injection molding method (1-K molding). The measured young's modulus E and quality factor Q are described in table 3.

Example 4 (optical recording medium)

The reflective and light transmissive layers described above were applied to the disk substrate of example 3. The scratch depth was determined to be 0.706 μm and the surface roughness was determined to be R_a8.06 nm. Test arms were prepared from the disk substrate as described in the single component injection molding method (1-K molding). The measured young's modulus E and quality factor Q are described in table 3.

Example 5 (substrate)

Compound (Compound 3) was prepared from 77.95 wt.% BPA-polycarbonate (Makrolon OD)Bayer MaterialScience), 10 wt.% Polymethylmethacrylate (PMMA)Degussa), 12 wt.% graphite Cond 5/99(Graphit kropfmuhl AG, Hauzenberg/germany) and 0.05 wt.% glycerol monostearate (Dimodan, Danisco/germany) were prepared by mixing the ingredients in a ZSK 25/4 extruder (Coperion Holding GmbH, Stuttgart/germany) and granulating the molten extruded strands (strands) after cooling in a water bath. These pellets were molded in a 1-K injection molding process in a single component injection molding process (1-K molding) into disks of 120mm diameter and 1.2mm thickness as described above using an Arburg 370U 70030/302-K injection molder equipped with a sandwich plate, Philips CD-Mould and DVD-ROM master stamper. Test arms were prepared from the disk substrate as described in the single component injection molding method (1-K molding). The measured young's modulus E and quality factor Q are described in table 3.

Example 6 (optical recording medium)

The reflective layer and the light-transmitting layer as described above were applied to the disk substrate of example 3. The scratch depth was determined to be 0.690 μm and the surface roughness was determined to be R_a3.7 nm. Test arms were prepared from the disk substrate as described in the single component injection molding method (1-K molding). The measured young's modulus E and quality factor Q are described in table 3.

Table 3: 1-K Molding

	Resin/compound	Density (g/cm)3)	E (GPa) at 2kHz	Q at 2kHz
					Example 1	Compound 1	1.297	4.46	103
Example 2	Compound 1	1.298	4.56	107
					Example 3	Compound 2	1.431	7.67	82.8
Example 4	Compound 2	1.427	7.46	93.1
					Example 5	Compound (I)3	1.245	4.91	69.0
Example 6	Compound 3	1.259	5.10	77.2
					Comparative example 1	BPA polycarbonate	1.190	2.53	167
Comparative example 2	Polystyrene	1.014	3.28	175

	Resin/compound	Density (g/cm)3)	E (GPa) at 2kHz	Q at 2kHz
					Comparative example 3	Compound 4	1.206	6.18	170

Example 7

A2-K interlayer injection molded disc of 120mm diameter and 1.2mm thickness was prepared from pellets of Compound 2 as the core resin described in example 3 and pellets of BPA-polycarbonate as the skin resin (Makrolon OD) using an Arburg 370U 70030/302-K injection molding machine equipped with a sandwich plate, Philips CD-Mould and DVD-ROM master stamper molds as described in the above two-component interlayer injection molding method (2-K molding)Bayer MaterialScience). The machine sets a skin material volume of 50% of the dose volume at the first shot blast and a core material volume of 50% of the dose volume at the second shot blast. The sprue was sealed with a skin material during the third shot blasting. Average core thickness d measured on the disk_CIs 57% of the total thickness and two average skin thicknesses d_S1And d_S2Respectively, 21.5% of the total thickness. Test arms were prepared from the disk substrate as described in the two-component sandwich injection molding method (2-K molding). The measured young's modulus E and quality factor Q are described in table 4.

Example 8

The reflective layer and the transparent layer as described aboveApplied to the disk substrate of example 7. The scratch depth was determined to be 0.665 μm and the surface roughness was determined to be R_a7.91 nm. Test arms were prepared from the disk substrate as described in the two-component sandwich injection molding method (2-K molding). The measured young's modulus E and quality factor Q are described in table 4.

Table 4: 2-K sandwich moulding

	Cortex layer	Core	Density (g/cm)3)	E (GPa) at 2kHz	Q at 2kHz
						Example 7	BPA polycarbonate	Compound 2	1.328	3.44	122
Example 8	BPA polycarbonate	Compound 2	1.324	3.51	136

Example 9

UV-bonded disks 120mm in diameter and 1.2mm in thickness were produced from BPA-polycarbonate (Makrolon OD) as described in the UV-bonding method (UV-bonding) above, using the configuration of the flow line II DVD-R from Sinkuus, supraBayer MaterialScience) pellets were molded into two half-pans of 0.6mm thickness. UV Binder from 67.9 wt.% Desmolux XPBayer MaterialScience，29.1wt.％Sartomer SRSartomer and 2.9 wt.% (Darocur)Ciba) of the same. The mixture of these components was mixed using a SpeedMixer^TMAccording to the state of the art known to those skilled in the art. The distribution of the UV binder on the spin stand and the UV curing are also carried out as described above by using a setup up to a thickness of the adhesive layer of-90 μm. Average adhesive layer thickness d measured on the disc_BIt was 89 μm. Test arms were prepared from the disk substrate as described in the UV-bonding method (UV bonding). The measured young's modulus E and quality factor Q are described in table 5.

Example 10

The reflective and light transmissive layers described above were applied to the disk substrate of example 9. The scratch depth was determined to be 0.523 μm and the surface roughness was determined to be R_a3.6 nm. Such asTest arms were prepared from the disk substrate as described in the UV-bonding method (UV bonding). The measured young's modulus E and quality factor Q are described in table 5.

Table 5: UV bonding

	Substrate	Binder	Density (g/cm)3)	E (GPa) at 2kHz	Q at 2kHz
						Example 9	BPA polycarbonate	Binder 1	1.187	2.19	14.0
Example 10	BPA polycarbonate	Binder 1	1.186	2.33	15.3

It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.

Claims (15)

1. An optical recording medium comprising a substrate, and a recording layer and a light-transmitting layer sequentially arranged on the substrate; wherein the substrate comprises one or more parts selected from the group consisting of an injection molded part, an injection molded sandwich structure having a molded surface layer and a molded core layer, or two UV-bonded injection molded parts, and combinations thereof; and wherein the substrate has a Young's modulus E of at least 2.15GPa and a quality factor of less than 160 when measured according to ASTM E756-05 at 25 ℃ and 2000 Hz.

2. Optical recording medium according to claim 1 wherein the substrate has a young's modulus E of at least 2.15GPa and a quality factor lower than 100, measured according to ASTM E756-05 at 25 ℃, 2000 Hz.

3. Optical recording medium according to claim 1 wherein the substrate has a young's modulus E of at least 2.93GPa and a quality factor lower than 160, measured according to ASTM E756-05 at 25 ℃, 2000 Hz.

4. The optical recording medium according to claim 1, wherein the light-transmitting layer comprises a UV-curable and spin-coatable resin having a refractive index such that the real part n is at least 1.41.

5. The optical recording medium according to claim 1, wherein the light transmitting layer comprises a UV curable and spin-coatable resin having: (i) a complex refractive index having a real part n of at least 1.70 and an imaginary part k of at most 0.016; (ii) surface roughness R below 20nm_a(ii) a And (iii) scratch resistance of no greater than 0.75 μm scratch depth; wherein the real part n and the imaginary part k of the complex refractive index are measured at a wavelength of 400-410 nm; wherein the surface roughness R_aDetermined by atomic force microscopy; and wherein the scratch depth is determined by moving a diamond needle having a tip radius of 50 μm on the light transmitting layer at an advancing speed of 1.5cm/s under application of a gravity of 40 g.

6. Optical recording medium according to claim 1, wherein the light transmitting layer comprises a UV curable and spin-coatable resin comprising a polymer having an average particle size (d)₅₀) Nanoparticles of less than 100 nm.

7. The optical recording medium according to claim 1, wherein the light-transmitting layer has a thickness of 1nm to less than 3000 nm.

8. The optical recording medium according to claim 1, wherein the light-transmitting layer has a thickness of 200nm to less than 2000 nm.

9. The optical recording medium according to claim 1, wherein the light-transmitting layer has a thickness of 500nm to less than 1500 nm.

10. The optical recording medium according to claim 1, wherein the substrate comprises a portion prepared by a 1-K injection molding method.

11. The optical recording medium according to claim 1, wherein the substrate comprises a portion prepared by a 2-K interlayer injection molding method.

12. The optical recording medium according to claim 1, wherein the substrate comprises two injection-molded substrates bonded by a UV-bonding method.

13. The optical recording medium according to claim 1, wherein the substrate comprises a resin selected from the group consisting of polycarbonate resins, acrylic resins, polystyrene resins, polycycloolefin resins, hydrogenated polystyrene resins, and combinations thereof.

14. The optical recording medium according to claim 1, wherein the substrate comprises a polycarbonate resin prepared with an aromatic dihydroxy monomer compound of the general formula (1):

HO-Z-OH(1)

wherein Z represents a group of formula (Ia):

wherein each R¹And R²Independently represent H or C₁-C₈-an alkyl group; and X represents a single bond, C₁-C₆Alkylene radical, C₂-C₅Alkylidene or optionally C₁-C₆-alkyl-substituted C₅-C₆-a cycloalkylene group; provided that when X represents 3, 3, 5 trimethylcyclohexylidene, R¹And R²Each represents hydrogen.

15. The optical recording medium according to claim 2, wherein the substrate comprises a resin selected from the group consisting of polycarbonate resin, acrylic resin, polystyrene resin, polycycloolefin resin, hydrogenated polystyrene resin, and a combination thereof.