WO2006120205A2

WO2006120205A2 - Anionic phthalocyanine based dyes for use as bca dye in an optical recording layer for blue laser recording

Info

Publication number: WO2006120205A2
Application number: PCT/EP2006/062182
Authority: WO
Inventors: Pascal Steffanut; Lars LÜCKE; Jean-Christophe Graciet; Martin Alexander Winter
Original assignee: Clariant International Ltd; Clariant Finance (Bvi) Limited
Priority date: 2005-05-10
Filing date: 2006-05-10
Publication date: 2006-11-16
Also published as: WO2006120205A3; TW200704721A

Abstract

The present invention relates to the use of anionic phthalocyanine based dyes as BCA (Burst Cutting Area) dye in optical layers for optical data recording, preferably for optical data recording using a laser with a wavelength from 380 to 650 nm. The invention further relates to an optical data recording medium capable of recording and reproducing information by laser beam irradiation. Particularly, it relates to a heat mode type optical data recording medium, which employs an anionic phthalocyanine based dye in the optical layer.

Description

ANIONIC PHTHALOCYANINE BASED DYES FOR USE AS BCA DYE IN AN OPTICAL RECORDING LAYER FOR BLUE LASER RECORDING

The present invention relates to the use of anionic phthalocyanine based dyes as BCA (Burst Cutting Area) dye in optical layers for optical data recording, preferably for optical data recording using a laser with a wavelength from 380 to 650 nm.

The invention further relates to an optical data recording medium capable of recording and reproducing information by laser beam irradiation. Particularly, it relates to a heat mode type optical data recording medium, which employs an anionic phthalocyanine based dye in the optical layer.

Optical data recording media (optical discs) capable of recording information only once with a laser beam are conventionally known. Such optical discs are also referred to as write-once CDs (compact discs, CD-Rs) and in a typical structure thereof, a recording layer (optical layer) comprising an organic compound such as an organic dye, a light reflective layer comprising a metal such as gold, and a protective layer made of a resin, are laminated successively, in this order, on a transparent disc-shaped substrate. Information is recorded to a CD-R by irradiating a near-infrared laser beam (usually a laser beam with a wavelength near 780 nm) thereon, in which the irradiated area of the recording layer absorbs the beam. The temperature of the irradiated area increases, causing the optical characteristics of the area to undergo physical or chemical changes (e.g. the formation of pits) and the information is thus recorded.

With regards to reading (reproduction) of information, this is also conducted by irradiating a laser beam with a wavelength identical to that of the recording laser beam. Information reproduction from the CD-R is conducted by detecting the difference of the reflectivity in the recording area between the areas where the optical characteristics have been changed (recorded area) and not changed (unrecorded area).

In recent years, there has been a demand for optical information recording media possessing higher recording density. To meet this demand for greater recording capacity, an optical disc referred to as a write-once digital versatile disc (DVD-R) has been proposed (for example, see Nikkei New Media special volume "DVD", published in 1995). The DVD-R is configured by appending two discs, each usually formed by laminating a recording layer containing an organic dye, a light reflective layer and a protective layer, in this order, on a transparent disc-shaped substrate in which guide grooves (pre-grooves) for laser beam tracking are formed. The pre-grooves occupy a narrow area of the DVD-R, specifically one-half or less of the DVD-R (0.74-0.8 μm) and the recording layers of the disc are formed towards the inner portion of the disc. The DVD-R can also be configured so that a disc-shaped protective substrate is included with the recording layer formed towards the inner portion of the disc. Information is recorded to and reproduced from the DVD-R by irradiating a visible laser beam thereon (usually a laser beam with a wavelength of about 630 nm to 680 nm), and thus, recording at a density higher than that of a CD-R is possible.

However, considering factors such as the recent spread of networks (e.g. Internet) and the emergence of high definition television (HDTV) broadcasting, cheap and convenient recording media, capable of recording image information at even larger capacity, are required. While DVD-R' s sufficiently serve as high-capacity recording media at present, demand for larger capacity and higher density has increased.

Blu-ray^® discs (Blu-ray^® disc is a standard developed by Hitachi Ltd., LG Electronics Inc., Matsushita Electric Industrial Co. Ltd., Pioneer Corporation, Royal Philips Electronics, Samsung Electronics Co. Ltd., Sharp Corporation, Sony Corporation, Thomson Multimedia) or HD-DVD discs (high density digital versatile disc), a standard developed by Toshiba and NEC) are going to be the next milestone in optical recording technology. Its new specification increases the data storage up to 27 Gigabytes per recording layer for a 12 cm diameter disc. By adopting a blue diode laser with a wavelength of 405 nm (GaN or SHG laser diodes), the pit size and track interval can be further reduced, again increasing the storage capacity by an order of magnitude.

Here also organic dyes have attracted considerable attentions and some solutions have been already proposed in the field of short wavelength diode-laser optical storage. Examples of such media include JP-A Nos. 4-74690, 7-304256, 7-304257, 8-127174, 11-53758, 11-334204, 11-334205, 11-334206, 11-334207, 2000-43423, 2000-108513, 2000-113504, 2000-149320, 2000-158818, and 2000-228028. In the methods described above, information is recorded and reproduced by irradiating a blue laser beam (wavelength: 430 nm, 488 nm) or blue-green laser beam (wavelength: 515 nm) onto an optical disc having a recording layer containing porphyrine compounds, azo dyes, metal azo dyes, quinophthalone dyes, trimethinecyanine dyes, dicyanovinylphenyl skeleton dyes, coumarin compounds and naphthalocyanine compounds.

The main information on a recording medium is recorded in an area that is located further on the outer peripheral side of the system read-in area at a predetermined interval and used for recording and reproduction of usual optical information (data information) by the laser beam used by general users. But, the main information is not limited to information recorded in the main data area. At a stage of shipment from a factory, in the optical information recording medium and mainly for copy protection, information needs also to be written in the sub-information area and the system read-in area by a writing device for BCA (burst cutting area)

As one of standards concerning the blue laser disc BD (BluRay® disc) or HD-DVD (high density digital versatile disc), it is necessary to perform this so called BCA (sub- information recording), in particular, in the sub-information area according to barcode recording after forming the optical recording. For a blue laser for a BD and an HD- DVD, an oscillation source having sufficient power has not be developed yet (maximum power is about 200 mW at present). Thus, in order to perform the BCA, an oscillation source of a red laser beam already used for a CD or a DVD (a red laser beam for a CD or a short wavelength red laser beam for a DVD, hereinafter referred to as "red laser") is used under the present circumstances.

It is an object of the invention to provide an optical information recording medium that is capable of realizing BCA required in standards of blue laser discs (a BD and an HD- DVD). It is another object of the invention to provide an optical information recording medium that has slight record sensitivity to a red laser while securing record sensitivity to a blue laser and a method of manufacturing the same.

It is still another object of the invention to provide an optical information recording medium that makes it possible to perform sub-information recording (BCA) in a sub- information area by a red laser and a method of manufacturing the same.

It is still another object of the invention to provide an optical information recording medium that makes it possible to perform BCA in a sub-information area with high power by a red laser and a method of manufacturing the same.

It is still another object of the invention to provide an optical information recording medium that makes it possible to perform BCA using barcodes in a sub-information area with high power and a method of manufacturing the same.

The invention further aims at selecting a dye having an absorption spectrum in a wavelength area of a red laser, as a light-absorbing material.

EP 1434207 A2 discloses a phthalocyanine dye of the formula

wherein R₃₁ to R₃₈ and R_b1 to R_b8 each independently represents one selected from the group consisting of a hydrogen atom, a halogen atom, a cyano group, a nitro group, a formyl group, a carboxyl group, a sulfo group, an alkyl group having 1 to 20 carbon atoms which may be substituted or unsubstituted, an aryl group having 6 to 14 carbon atoms which may be substituted or unsubstituted, a heterocyclic group having 1 to 10 carbon atoms which may be substituted or unsubstituted, an alkoxy group having 1 to 20 carbon atoms which may be substituted or unsubstituted, an aryloxy group having 6 to 14 carbon atoms which may be substituted or unsubstituted, an acyl group having 2 to 21 carbon atoms which may be substituted or unsubstituted, an alkylsulfonyl group having 1 to 20 carbon atoms which may be substituted or unsubstituted, an arylsulfonyl group having 6 to 14 carbon atoms which may be substituted or unsubstituted, a heterylsulfonyl group having 1 to 10 carbon atoms, a carbamoyl group having 1 to 25 carbon atoms which may be substituted or unsubstituted, a sulfamoyl group having 0 to 32 carbon atoms which may be substituted or unsubstituted, an alkoxycarbonyl group having 2 to 20 carbon atoms which may be substituted or unsubstituted, an aryloxycarbonyl group having 7 to 15 carbon atoms, an acylamino group having 2 to 21 carbon atoms which may be substituted or unsubstituted, or a sulfonylamino group having 1 to 20 carbon atoms which may be substituted or unsubstituted. In formula (I), all of R_a1 to R_a8 are not simultaneously hydrogen atoms, and at least eight of the substituents of R₃₁ to R₃₈ and R_b1 to R_b8 are hydrogen atoms. M represents two hydrogen atoms, a divalent- to tetravalent-metal, a divalent- to tetravalent- metal oxide, or a divalent- to tetravalent-metal having a ligand

EP 1434207 A2 further discloses the use of said phthalocyanine dye in a dye recording layer for an optical information recording medium.

Surprisingly it has now been found, that specific anionic phthalocyanine based dyes as described below are useful as dye component for BCA encoding in optical layers for optical data recording media. These products show very interesting recording characteristics and excellent overall performances when applied together with recording dyes of various types in recording media. In addition, the anionic phthalocyanine based dyes possess high light stability, read-out stability and sufficient reflectivity to be used on production lines.

The present invention therefore relates to anionic phthalocyanine based dyes for use in an optical layer comprising anionic phthalocyanine based dyes as described below and to the use of said optical layers for optical data recording media. Particularly, the invention relates to a heat mode type optical data recording medium, which employs an anionic phthalocyanine based dye in the optical layer. More particularly, the invention relates to a write once read many (WORM) type optical data recording medium capable of recording and reproducing BCA information with radiation of a red laser of preferably 650 nm, which employs an anionic phthalocyanine based dye in the optical layer, the phthalocyanine based dye preferably being used as a BCA dye. In the following text "halogen" represents F, Cl, Br or I, preferably F, Cl or Br, more preferably F or Cl, even more preferably Cl, if not otherwise stated; "alkyl" represents linear and branched alkyl; and "alkoxy" represents linear and branched alkoxy; any alkyl and cycloalkyl groups being unsubstituted or substituted by halogen; if not otherwise stated.

The present invention is directed to a compound of formula (I)

wherein

MA is a divalent metal atom selected from the group of metals consisting of Mg, Mn, Co, Cr, Fe, Ni, Cu, Zn, Al and Pd, preferably from the group consisting of Cu, Ni and Pd, more preferably MA is Cu;

R¹ to R¹⁵ independently from each other are selected from the group consisting of H, Ci-I₀ alkyl, Ci-I₀ alkoxy, SO₃ ^", SO₂NR¹⁶R¹⁷, with R¹⁶ and R¹⁷ independently from each other being selected from the group consisting of H, Ci-I₀ alkyl, Ci-I₀ alkoxy, C_5-I₀ cycloalkyl, C_2-I₀ alkyl-Ci-io alkoxy, unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents independently from each other selected from the group consisting of halogen, Ci_-I0 alkyl and nitro, and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents independently from each other selected from the group consisting of halogen, Ci_-I0 alkyl and nitro; CN, COO^" and Ci-I₀ alkyl carboxylate; Cat⁺ is selected from the group of cations consisting of cyanine type cations, preferably of formula (a) and (b), hemicyanine type cations, preferably of formula (c), triarylmethane type cations, preferably of formula (d), pyridinium type cations, preferably of formula (e), guanidinium type cations, preferably of formula (f) and ammonium type cations, preferably of formula (g,h,i);

(a) (b)

(e) (f»

R19— N ?₊— R18 H— N-Rl 8 H— N-Rl 8

R20 R19 H

(g) (h) (0

wherein R¹⁸, R¹⁹, R²⁰, R²¹, R²² independently from each other are a C_1-30-hydrocarbon; preferably R¹⁸, R¹⁹, R²⁰, R²¹, R²² independently from each other are selected from the group consisting of dehydroabietyl radical (the dehydroabietyl radical derived from dehydroabietylamine ((4β)-abieta-8, 11,13- trien-18-amine)), C_1-10 alkyl, preferably C_1-4 alkyl, unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents independently from each other being selected from the group consisting of halogen, C_1-10 alkyl and nitro, and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents independently from each other being selected from the group consisting of halogen, C_1-10 alkyl and nitro; preferably at least one, more preferably 1, 2, 3 or 4, even more preferably 1, 2 or 3, especially 2 or 3, of the substituents R¹ to R¹⁵ being SO₂NR¹⁶R¹⁷, with R¹⁶ and R¹⁷ having the above definition; preferably R¹⁶ being H; preferably R¹⁷ being C_1-10-alkyl or C_2-10 alkyl-C_1-10-alkoxy, more preferably C_1-8 alkyl or C_2-4 alkyl-Ci-4 alkoxy, even more preferably C₈ alkyl or C_2-4 alkyl-C_1-2 alkoxy, especially 2-ethyl-hexyl or methoxypropyl; and the other substituents of R¹ to R¹⁵, which are not SO₂NR¹⁶R¹⁷, being H; preferably Cat⁺ is selected from the group of cations consisting of cyanine type cations of formula (a), triarylmethane type cations of formula (d), guanidinium type cations of formula (f) and ammonium type cations of formula (g,h,i), more preferably from the group of cations consisting of guanidinium type cations of formula (f) and ammonium type cations of formula (g); wherein R , R and R independently from each other are a C_1-30-hydrocarbon, preferably R¹⁸, R¹⁹ and R²⁰ independently from each other are a dehydroabietyl radical, the dehydroabietyl radical derived from dehydroabietylamine ((4β)- abieta-8,l l,13-trien-18-amine), or C_1-10 alkyl, more preferably R¹⁸, R¹⁹ and R²⁰ independently from each other are a C_1-4 alkyl, even more preferably R¹⁸, R¹⁹ and R²⁰ independently from each other are selected from the group consisting of methyl, ethyl and isopropyl; and wherein R²¹, R²² independently from each other are unsubstituted phenyl or substituted phenyl, with 1 to 2 substituents independently from each other being C_1-2 alkyl, preferably R²¹ and R²² are independently from each other phenyl or tolyl. In a preferred aspect, the present invention is directed to a compound of formula (I) wherein

MA is selected from the group consisting of Cu, Ni, Pd, preferably MA is Cu; and at least one, preferably 1, 2, 3 or 4, more preferably 1, 2 or 3, even more preferably 2 or

3, of the substituents R¹ to R¹⁵ are SO₂NR¹⁶R¹⁷, with R¹⁶ being H and R¹⁷ being C_1-10 alkyl or C_2-10 alkyl-C_1-10 alkoxy, preferably C_1-8 alkyl or C2-4 alkyl-Ci-4 alkoxy, more preferably C₈ alkyl or C2-4 alkyl-Ci-2 alkoxy, especially 2-ethyl-hexyl or methoxypropyl; and the other substituents of R¹ to R¹⁵, which are not SO₂NR¹⁶R¹⁷, are

H; and

Cat⁺ is selected from the group of cations consisting of guanidinium type cations of formula (f) and ammonium type cations of formula (g), wherein R , R and R independently from each other are of C_1-4 alkyl, preferably R , R and R are independently from each other selected from the group consisting of from the group consisting of methyl, ethyl and isopropyl, and wherein R²¹ and R²² independently from each other are phenyl or tolyl.

In a more preferred aspect, the present invention is directed to a compound of formula

(I) wherein

MA is Cu; at least one, preferably 1, 2, 3 or 4, more preferably 1, 2 or 3, even more preferably 2 or

3, of the substituents R¹ to R¹⁵ are SO₂NR¹⁶R¹⁷, with R¹⁶ being H and R¹⁷ being n- propyl, methoxypropyl or 2-ethy-hexyl; and the other substituents of R¹ to R¹⁵, which are not SO₂NR¹⁶R¹⁷, are H; and

Cat⁺ is selected from the group of cations consisting of guanidinium type cations of formula (f) and ammonium type cations of formula (g), wherein R , R and R independently from each other are selected from the group consisting of methyl, ethyl and isopropyl, and wherein R²¹, R²² independently from each other are phenyl or tolyl.

The compounds of formula (I) are prepared by reacting the protonated species of the sulfonated phthalocyanine dye (the anion in formula (I)) or an alkaline earth salt, preferably the sodium salt, of the sulfonated phthalocyanine dye with a compound comprising the Cat+ (the cation in formula (I)), e.g. with the deprotonated species of Cat+, preferably with a salt, which comprises as a cation the Cat+, more preferably with a halide of Cat+, even more preferably with a chloride of Cat+. The reaction can be carried out in solid or liquid state, preferably in suspension or in solution.

An optical layer according to the invention comprises at least one compound of formula (I) or a mixture of preferably 2 to 10, more preferably 2 to 5, even more preferably 2, 3, or 4, compounds of formula (I).

A further aspect of the invention is an optical layer comprising at least one compound of formula (I) and at least one, preferably 1 to 5, more preferably 1, 2 or 3, even more preferably 1 or 2, compound of formula (II),

wherein

MB represents a divalent metal atom;

R 21 is selected from H, C_1-10 alkyl, C_5-10 cycloalkyl, C_1-10 alkoxy, unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents independently from each other being selected from the group consisting of halogen, C_1-10 alkyl and nitro; unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents independently from each other being selected from the group consisting of halogen, C_1-10 alkyl and nitro; COO^" or C_1-10 alkyl carboxylate; R²² is selected from C_1-10 alkyl or C_5-10 cycloalkyl;

R²³ is selected from H, Cl, CN, Br, CF₃, C_1-8 alkyl, chloromethyl, C_1-8-alkoxymethyl, phenoxymethyl, NO₂ or sulfonamide; R²⁴ is selected from H, C_1-10 alkyl, C_5-10 cycloalkyl, C_1-10 alkoxy, unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents independently from each other being selected from the group consisting of halogen, C_1-10 alkyl and nitro; unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents independently from each other being selected from the group consisting of halogen, C_1-10 alkyl and nitro; COO^" or C_1-10 alkyl carboxylate; R²⁵ is selected from hydrogen, C_1-10 alkyl, C_5-10 cycloalkyl, C_1-10 alkoxy, unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents independently from each other being selected from the group consisting of halogen, C_1-10 alkyl and nitro; unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents independently from each other being selected from the group consisting of halogen, C_1-10 alkyl and nitro; COO^" or C_1-10 alkyl carboxylate.

The compounds of formula (II) are recording dyes and are known compounds. They are described for example in patent WO2006/013214.

The compounds of formula (I) act are used preferably as BCA dyes. Therefore a further subject of the invention is the use of compounds of formula (I) as BCA dyes in optical layers of optical data recording mediums, preferably together with compounds of formula (II) as recording dyes.

Preferably, the mixture of compounds of formula (I) and (II) comprises at least one compound of formula (II) wherein

MB is selected from the group consisting of Ni, Cu, Co, Zn, Al, Fe, Pd, Pt, Cr and

Mn;

R²¹ is selected from CH₃, C₂H₅, C₃H₇ or unsubstituted phenyl, R²² is selected from CH₃ or C₂H₅, R²³ is selected from H, Cl, CH₃, C₂H₅ or NO₂,

R²⁴ is hydrogen, CH₃ or C₂H₅,

R²⁵ is selected from unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents independently from each other being selected from the group consisting of halogen, C_1-10 alkyl and nitro.

In a more preferred aspect, the mixture of compounds of formula (I) and (II) comprises at least one compound of formula (II- 1),

wherein MC is selected from the group consisting of Ni, Cu, Co, Zn, Al, Fe, Pd, Pt, Cr and Mn; preferably MC is selected from the group consisting of Ni, Cu, Co, Zn and Cr, more preferably MC is selected from the group consisting of Ni, Cu and Zn, even more preferably Cu and Ni, especially Cu.

The optical layers according to one aspect the invention comprise a compound of formula (I) or a mixture of such compounds preferably in an amount sufficient to have a substantial influence on the refractive index, for example at least 5% by weight, more preferably at least 10% by weight, most preferably at least 20% by weight of the main recording dye.

Further, the invention relates to a method for producing an optical layer, comprising the following steps

(a) providing a substrate

(b) dissolving a compound or a mixture of compounds of formula (I) in an organic solvent to form a solution,

(c) coating the solution (b) on the substrate (a);

(d) evaporating the solvent to form a dye film.

In a preferred aspect of the invention, the optical layer comprises a mixture of at least one compound of formula (I) and of at least one main recording dye of formula (II).

A preferred method for producing an optical layer according to the invention therefore comprises the following steps

(a) providing a substrate

(b) dissolving a mixture of one or more of compounds of formula (I) and one or more of compounds of formula (II) in an organic solvent to form a solution,

(c) coating the solution (b) on the substrate (a);

(d) evaporating the solvent to form a dye layer.

As a substrate, various kinds of materials can be used, for example, glass, polycarbonates, acrylic resins such as polymethylmethacrylate; vinyl chloride resins such as polyvinyl chloride and polyvinyl chloride copolymers; epoxy resins; amorphous polyolefins; polyesters; and metals such as aluminum. Among them, polycarbonates and amorphous polyolefins are preferred, with polycarbonates being particularly preferred in view of the moisture proof ness, dimensional stability and low cost.

Optionally a light reflection layer is disposed to the substrate. For to the light reflection layer, a light reflecting material having a high reflectance to laser beam is used. The reflectance is preferably 70% or more. Suitable light reflecting material are selected from metals and semimetals such as Mg, Se, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Co, Ni, Ru, Rh, Pd, Ir, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Si, Ge, Te, Pb, Po, Sn and Bi, or stainless steels. The light reflecting material may be used alone or may be used in a combination of two or more of them, or as an alloy. Among them preferred are Cr, Ni, Pt, Cu, Ag, Au and Al, as well as stainless steels. Particularly preferred are Au, Ag, Al or alloys thereof and most preferred are Au, Ag or alloys thereof. The light reflection layer can be formed on the substrate, for example, by vapor depositing, sputtering or ion plating. The thickness of the light reflection layer is, generally, within a range of from 10 to 300 nm and, preferably, within a range from 50 to 200 nm.

The optical layer can be formed, for example, by vapor deposition, sputtering, CVD, or solvent coating. The preferred methods are solvent coating or vapor deposition. The most preferred method is solvent coating.

For solvent coating, the compound of the invention described above is dissolved in a solvent and, optionally, a quencher and/or a binder is added to prepare a coating solution. The coating solution is then coated to the surface of the substrate (or onto the light reflection layer on the substrate) and then dried.

Suitable organic solvents for coating are selected from C_1-8 alcohol, halogen substituted C_1-8 alcohols, C_1-8 ketone, C_1-8 ether, halogen substituted C_1-4 alkane, or amides. Preferred C_1-8 alcohols or halogen substituted C_1-8 alcohols are for example methanol, ethanol, isopropanol, diacetone alcohol (DAA), 2,2,3, 3-tetrafluoropropanol (TFP), trichloroethanol, 2-chloroethanol, octafluoropentanol or hexafluorobutanol. Preferred C_1-8 ketones are for example acetone, methylisobutylketone, methylethylketone, or 3-hydroxy-3-methyl-2-butanone. Preferred halogen substituted C_1-4 alkanes are for example chloroform, dichloromethane or 1-chlorobutane. Preferred amides are for example dimethylformamide or dimethylacetamide.

The coating method is selected from spraying, spin coating, dipping, roll coating, blade coating, and screen printing. The coating temperature is from 10 to 50^° C, preferably from 24 to 40^° C. and, more preferably, from 25 to 37^° C.

The most preferred coating method is spin-coating. The most preferred solvents are 2- methoxyethanol, n-propanol, isopropanol, isobutanol, n-butanol, amyl alcohol or 3- methyl-1-butanol or preferably fluorinated alcohols, e.g. 2,2,2-trifluoroethanol or 2,2,3, 3-tetrafluoro-l-propanol, octafluoropentanol and mixtures thereof.

The obtained optical layer may be a single layer or a stacked layer and the thickness of the optical layer is, generally, within a range from 20 to 500 nm, more preferably, within a range from 30 to 300 nm, most preferably, within a range from 50 to 100 nm. An optical data recording medium according to the invention comprises on an optical layer on a substrate capable of recording information by irradiation of a laser beam, wherein the optical layer contains the compound represented by the general formula (I) or a mixture comprising at least one dye compound of formula (I) and at least one dye compound of formula (II).

A method for producing an optical recording medium comprising an optical layer according to the invention comprises the following additional steps:

(e) sputtering a metal layer onto the dye layer

(f) applying a second polymer based layer to complete the disc.

A high-density optical recording medium according to the invention therefore preferably is a recordable optical disc comprising: a first substrate, which is a transparent substrate with grooves, a recording layer (optical layer), which is formed on the first substrate surface using the compounds of formula (I), a reflective layer formed on the recording layer, a second substrate, which is a transparent substrate with grooves connected to the reflective layer with an attachment layer.

Readout methods

The structure of the optical data recording medium according to the invention is governed primarily by the readout method; known function principles include the measurement of the change in the transmission or, preferably, in the reflection, but it is also known to measure, for example, the fluorescence instead of the transmission or reflection.

When the optical data recording medium is structured for a change in reflection, the following structures can be used: transparent support / recording layer (optionally multilayered) / reflective layer and, if expedient, protective layer (not necessarily transparent); or support (not necessarily transparent) / reflective layer / recording layer and, if expedient, transparent protective layer. In the first case, the light is incident from the support side, whereas in the latter case the radiation is incident from the recording layer side or, where applicable, from the protective layer side. In both cases the light detector is located on the same side as the light source. The first-mentioned structure of the recording material to be used according to the invention is generally preferred. When the optical data recording medium is structured for a change in light transmission, the following different structure comes into consideration: transparent support/ recording layer (optionally multilayered) and, if expedient, transparent protective layer. The light for recording and for readout can be incident either from the support side or from the recording layer side or, where applicable, from the protective layer side, the light detector in this case always being located on the opposite side. Suitable lasers are those having a wavelength of 350-500 nm, for example commercially available lasers having a wavelength of 405 to 414 nm, especially semi-conductor lasers. The recording is done, for example, point for point, by modulating the laser in accordance with the mark lengths and focusing its radiation onto the recording layer. It is known from the specialist literature that other methods are currently being developed which may also be suitable for use.

The process according to the invention allows the storage of information with great reliability and stability, distinguished by very good mechanical and thermal stability and by high light stability and by sharp boundary zones of the pits. Special advantages include the high contrast, the low jitter and the surprisingly high signal/noise ratio, so that excellent readout is achieved.

The readout of information is carried out according to methods known in the art by registering the change in absorption or reflection using laser radiation.

The invention accordingly relates also to a method for the optical data recording, storage and playback of information, wherein an optical data recording medium according to the invention is used. The recording and the playback advantageously take place in a wavelength range of from 350 to 500 nm.

A further subject of the invention therefore is the use of the compounds of formula (I) as BCA marking dyes in blue laser optical recording discs.

The use of compounds of formula (I) results in advantageously homogeneous and amorphous films, providing for low-scattering optical layers having a high refractive index. The absorption edge is surprisingly steep even in the solid phase. Further advantages are high light stability in daylight and under laser radiation of low power density with, at the same time, high sensitivity under laser radiation of high power density, uniform script width, high contrast, and also good thermal stability and storage stability.

It has been found, that the compounds of formula (I) according to the invention enhance the photosensitivity and the stability to light and heat compared to dyes already known in the art. The compounds of formula (I) according to the invention have a decomposition temperature of 250-350°C. Additionally, these compounds show an extremely good solubility in organic solvents, which is ideal for the spin-coating process to manufacture optical layers.

Thus, it is of great advantage to use these new compounds in the recording layer of high-density recordable optical discs.

The compounds of formula (I) when combined with dyes of formula (II) provide for particularly preferable properties when used in optical layers for optical data recording media according to the invention. They possess the required optical characteristics, demonstrated when used in the form of a solid film:

• an advantageously homogeneous, amorphous and low-scattering optical layer,

• a high refractive index at the longer wavelength flank of the absorption band, which preferably achieves n values of the refractive index of from 1.0 to 3.0 in the range of from 350 to 500 nm,

• a high sensitivity under laser radiation of high power density and good playback characteristics in the desired spectral range,

• an enhanced photosensitivity and stability (in daylight and under laser radiation of low power density ) compared to dyes already known in the art,

• an uniform script width and a high contrast,

• an absorption maximum λ max in the preferred range between 390 nm and 470 nm as being preferred for blue laser applications, more precisely from 400 to 460 nm,

• a decomposition point DP in the preferred temperature range between 220°C and 300°C, more precisely 230°C to 290°C

• a sufficient heat release (HR) Recording performance of a compound is related to specific parameters measured on disc like:

• a low simulated bit error rate (SbER)

• a low inner parity error rate (PI error)

• a high reflectivity (R)

• a low laser recording power (Pw or OPC: optimum power control)

• good readout stability at several laser reading powers.

• an appropriate partial response signal to noise ratio (PRSNR)

Examples

UV-vis

For UV-vis spectra, λ max and ε values of a compound are determined by using an UV- vis spectrophotometer, the compound or mixture was dissolved in CH2CI2, DMSO or in TFP. The values are obtained by balancing the measurements performed on compound solutions at three different concentrations.

Thermal Decomposition: Decomposition point (DP) and heat release (HR) For the determination of DP and HR, the compound or mixture is incorporated into a sealed aluminum pan. Analysis conditions are as following: Temperature range from 25 to 400°C, heating rate 10°C/min, nitrogen flow of 50 ml/min. Values are determined by single measurement.

Partial response signal to noise ratio (PRSNR)

A definition and the measuring techniques of PRSNR are described in a book available from DVD Format Logo Licensing Co., Ltd. for example, Annex H of Version 0.9, PART 1 Physical Specifications, DVD Specifications for High Density Read-Only Disk.

Simulated bit error rate (SbER)

A definition and the measuring techniques of SbER are described in a book available from DVD Format Logo Licensing Co., Ltd. for example, Annex H of Version 0.9, PART 1 Physical Specifications, DVD Specifications for High Density Read-Only Disk.

PRSNR and SbER are measured in a state in which information has been recorded in the adjacent tracks.

Reflectivity (R)

A definition and the measuring techniques for the light reflectivity (R) is described in a book available from DVD Format Logo Licensing Co., Ltd. for example, Annex D of Version 0.9, PART 1 Physical Specifications, DVD Specifications for High Density Read-Only Disk. All phthalocyanine/cationic counter ion dye compounds of formula (I) were prepared using standard procedures known in the art, involving reaction of the appropriate anionic sulfonated phthalocyanine with the corresponding chloro salt of the trialkylammonium or the guanidinium type cation in a 1 : 1 molar ratio in a mixture of water and ethanol. The phthalocyanine/cationic counter ion dye compounds can be purified by recrystallization e.g. from an alcohol.

The sulfonated phthalocyanine salt is prepared, following classical methods known in the state of the art, by chlorosulfonation of the pigment blue 15 in chlorosulfonic acid and treatment of the obtained salt with different primary amines. This dyestuff solution after titration is used tel-quel in the examples below described.

The stoechiometry of the different reactants in the chlorosulfonation reaction is carefully chosen to obtain two or three sulfonamide groups and one sulfonate group. The substitution pattern observed by quantitative analysis is usually a statistical mixture of ortho, meta and para substituted compounds with an average of two sulfonamide groups at two different rings and one sulfonate group on a third ring. This analytically difficult situation is represented by the substituents "-SO₃ " and "R-Sulfonamide" in the formula (l)-(4). The primary amines used in the examples were methoxypropyl amine and 2-ethyl-hexyl amine.

Example A: Preparation of the sulfonated phthalocyanine salt with methoxypropyl amine

34 grams of pigment blue 15 are admixed into 100 ml of chlorosulfonic acid. The solution is heated up to 70°C and 51 grams of thionyl chloride are slowly added. The reaction temperature is kept for 8 hours and cooled down to 40°C. The solution is then hydro lysed slowly by pouring onto 300 ml of a water/ice mixture. 5 grams of hydrogen peroxide are added. The blue precipitate obtained is filtered and washed with water. The press cake is then poured into an aqueous solution of 16 grams of methoxypropylamine and heated up to 70°C for 5 hours while keeping the pH around 9.0 with sodium hydroxide. A suspension of compound A was obtained; it is used as starting material for the anion exchange described below.

Example B: Preparation of the sulfonated phthalocyanine salt with 2-cthyl-hcxyl amine

The procedure of example A was carried out with the sole difference, that 2-ethyl- hexyl-amine was used instead of methoxy-propylamine. A suspension of compound (B) was obtained, it is used as starting material for the anion exchange described below.

Example C: Preparation of the sulfonated phthalocyanine salt with 2-cthyl-hcxyl amine and methoxypropylamine

The procedure of example A was carried out with the sole difference, that a mixture of 2-ethyl-hexyl-amine and methoxypropylamine was used instead of methoxypropylamine alone in the equivalent stoechiometric amount. A suspension of compound (C) was obtained; it is used as starting material for the anion exchange described below.

Example 1

2.4 parts of a suspension of compound (A), obtained according to example A, is reacted at room temperature with a solution of 2.5 parts of {4-[bis-(4-dimethylamino-phenyl)- methylene]-cyclohexa-2,5-dienylidene}-dimethylammonium chloride (e.g. commercial product known as crystal violet (Basic violet 3)) in 50 parts of ethanol. The resulting precipitate is stirred for one hour, filtered and the residue is washed salt free with deionized water and dried. 4.0 g of a compound of formula (1) was obtained.

UV-Vis(TFP)λ_max:675nm; ε (λ_max): 124750 Lmor -1.cm -1 Example 2

The preparation according to example 1 is carried out with the only difference, that the so-called Rosine Amine D (dehydroabietylamine: (4β)-abieta-8,l l,13-trien-18-amine) is replacing the crystal violet. 3.7 g of a compound of formula (2) was obtained.

UV- Vis (EtOH) λ_max: 677 nm; ε (λ_max): 85400 l.mor -1.cm -1

Example 3

The preparation according to example 1 is carried out with the only difference, that 1- ethyl-2- [3 -( 1 -ethyl-3 ,3 -dimethyl- 1 ,3 -dihydro-benzindol-2-ylidene)-propenyl] -3 ,3 - dimethyl-3H-benzindolium iodide is replacing the crystal violet. 4.2 g of a compound of formula (3) was obtained.

Example 4

The preparation according to example 1 is carried out with the only difference, that diisopropyl-ethyl ammonium chloride is replacing the crystal violet. 3.5 g of a compound of formula (4) was obtained.

UV-Vis (TFP) λ_max: 657nmε (λ_max): 122000 l.mor -1.cm -1

Example 5

2.4 parts of a suspension of compound (B), obtained according to example B, is reacted at room temperature with a solution of 2.5 parts of triethylammonium chloride, in 50 parts of ethanol. The resulting precipitate is stirred for one hour, filtered and the residue is washed salt free with deionized water and dried. 3.8 g of a compound of formula (5) was obtained.

UV-Vis(TFP)λ_max:669nm; ε (λ_max): 1405866 l.mor i-l.cm -1 Example 6

2.4 parts of a suspension of compound (B), obtained according to example B, is reacted at room temperature with a solution of 2.5 parts of diphenylguanidinium chloride in 50 parts of ethanol. The resulting precipitate is stirred for one hour, filtered and the residue is washed salt free with deionized water and dried. 4.3 g of a compound of formula (6) was obtained.

UV-Vis(TFP)λ_max:671nm; ε (λ_max): 1157885 LmoP i-l.cm -1

Example 7

2.4 parts of a suspension of compound (C), obtained according to example C, is reacted at room temperature with a solution of 2.5 parts of ditolylguanidinium chloride in 50 parts of ethanol. The resulting precipitate is stirred for one hour, filtered and the residue is washed salt free with deionized water and dried. 4.4 g of a compound of formula (7) was obtained.

UV-Vis(TFP)λ_max:670nm; ε (λ_max): 1220318 LmoP i-l.cm -1 Mixtures

A mixture (ml), consisting of 10 % by weight of compound of formula (1) and 90 % by weight of compound of formula (II- 1), based on the total weight of the mixture, is prepared by blending the powders.

Similarly further 6 mixtures (m2) to (m7), consisting of 10 % by weight of compounds of formulae (2) to (7), respectively, and 90 % by weight of compound of formula (II- 1), based on the total weight of the mixture, are prepared.

Details are given in Table A.

Application example 1: Optical and thermal properties of the mixtures

Optical and thermal properties of the mixtures (ml) to (m7), that were present in the dye layers prepared according to examples 8 to 14, were studied. They show high absorption at the desired wavelengths.

Sharp thresholds of thermal decomposition in the required temperature range characterize these mixtures, which are assumed to be desirable for the application in optical layers for optical data recording.

Application Example 2 - Optical layer and optical data recording medium with the mixtures

Example 8

1.0 g of the mixture (ml) is dissolved in 50 ml of tetrafluoro-propanol and stirred at room temperature for 5 hours. The solution was filtered with a Teflon filter (having 0.2 μm pore size) and applied by spin-coating at 1000 rpm to the surface of a 0.6 mm thick, grooved polycarbonate disc of 120 mm diameter. The excess solution is spun off by increasing the rotational speed. On evaporation of the solvent, the dye remains behind in the form of a uniform, amorphous solid layer, the optical layer. After drying the optical layer in a circulating-air oven at 70°C (10 min) in a vacuum coating apparatus, a 100 μm thick silver layer is then applied to the recording layer by atomization. Then a 6 μm thick protective layer of a UV curable photopolymer (650-020, DSM) is applied thereto by means of spincoating. Finally, a second substrate is provided to combine with the resin protection layer using an attachment layer. This completes the manufacturing of a high-density recordable optical disc, the optical data recording medium.

Examples 9-14

6 further optical discs were prepared according to the procedure of example 8 with the difference, that the mixtures (m2) to (m7), respectively, were used instead of the mixture (ml).

Disc properties

Evaluation tests are performed using an optical disk evaluation device available from Pulse Tech Co., Ltd.

The testing conditions are the following ones:

• Numerical aperture (NA) of the optical head: 0.65

• Wavelength of a laser light for recording and reproduction: 405 nm

• Constant linear velocity (CLV): 6.61 m/sec.

• Track pitch: 400 nm

• Wobble amplitude of the groove track: 14 nm

• Groove depth: 90 nm.

A test for evaluating a degree of degradation due to repetition reproduction is conducted for each of the write-once optical disks made for the described dye recording layers. Readings are carried out at a reading laser power of 0.4 mW and the degrees of degradation of PRSNR and SbER are then measured. Maximum cycle number was found within the specifications Results obtained are summarized in the table (B).

The optical discs made with the 7 mixtures (ml) to (m7), prepared according to examples 8 to 14, showed improved recording characteristics and excellent overall performances when applied as recording media. The compounds of formula (I) (anionic phthalocyanine based dyes) when combined with a recording dye of formula (II), especially of formula formula (II- 1), provide high light stability, read-out stability and sufficient reflectivity to be used on high density digital versatile discs manufacturing and the so-obtained optical recording media are found fully within specifications.

Claims

1. A dye compound of formula (I)

wherein

MA is a divalent metal atom selected from the group of metals consisting of Mg, Mn,

Co, Cr, Fe, Ni, Cu, Zn, Al and Pd;

R¹ to R¹⁵ independently from each other are selected from the group consisting of H, Ci-I₀ alkyl, Ci-I₀ alkoxy, SO₃ ^", SO₂NR¹⁶R¹⁷, with R¹⁶ and R¹⁷ independently from each other being selected from the group consisting of H, Ci-I₀ alkyl, Ci-I₀ alkoxy, C_5-I₀ cycloalkyl, C_2-I₀ alkyl-Ci-io alkoxy, unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents independently from each other selected from the group consisting of halogen, Ci_-I0 alkyl and nitro, and unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents independently from each other selected from the group consisting of halogen, Ci_-I0 alkyl and nitro; CN, COO^" and Ci-I₀ alkyl carboxylate;

Cat⁺ is selected from the group of cations consisting of cyanine type cations, hemicyanine type cations, triarylmethane type cations, pyridinium type cations, guanidinium type cations and ammonium type cations.

2. A compound according to claim 1, wherein

MA is selected from the group consisting of Cu, Ni and Pd;

Cat⁺ is selected from the group of cations consisting of cyanine type cations of formula (a) and (b), hemicyanine type cations of formula (c), triarylmethane type cations of formula (d), pyridinium type cations of formula (e), guanidinium type cations of formula (f) and ammonium type cations of formula (g,h,i),

(a) (b)

(e) CO

R19— N— R18 H— N-Rl 8 H— N-Rl 8

R20 R19 H

(g) (h) (0

wherein R ₅ R ₅ R ₅ R and R independently from each other are a C_1-30-hydrocarbon; at least one of the substituents R¹ to R¹⁵ being SO₂NR¹⁶R¹⁷, with R¹⁶ being H and R¹⁷ being C_1-10-alkyl or C_2-10 alkyl-C_1-10-alkoxy, and the other substituents of R¹ to R¹⁵, which are not SO₂NR¹⁶R¹⁷, being H.

3. A compound according to claim 1 or 2, wherein

Cat⁺ is selected from the group of cations consisting of guanidinium type cations of formula (f) and ammonium type cations of formula (g),

8

(g)

(f> wherein R¹⁸, R¹⁹ and R²⁰ independently from each other are C_1-4 alkyl, and wherein R²¹, R²² independently from each other are phenyl or tolyl.

4. A compound according to one or more of claims 1 to 3, wherein MA is Cu;

1, 2, 3 or 4 of the substituents R¹ to R¹⁵ are SO₂NR¹⁶R¹⁷, with R¹⁶ being H and R¹⁷ being n-propyl, methoxypropyl or 2-ethy-hexyl; and the other substituents of R¹ to R¹⁵, which are not SO₂NR¹⁶R¹⁷, are H;

8

(g)

(f> wherein R 18₅ τR.19 and R independently from each other are selected from the group consisting of methyl, ethyl and isopropyl, and wherein R²¹, R²² independently from each other are phenyl or tolyl.

5. An optical layer comprising at least one compound according to formula (I) as defined in one or more of claims 1 to 4.

6. An optical layer according to claim 5 comprising at least one compound of formula (II),

wherein

MB represents a divalent metal atom;

R²¹ is selected from H, C_1-10 alkyl, C_5-10 cycloalkyl, C_1-10 alkoxy, unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents independently from each other being selected from the group consisting of halogen, C_1-10 alkyl and nitro; unsubstituted benzyl or substituted benzyl, with 1 to 4 substituents independently from each other being selected from the group consisting of halogen, C_1-10 alkyl and nitro; COO^" or C_1-10 alkyl carboxylate; R²² is selected from C_1-10 alkyl or C_5-10 cycloalkyl;

7. An optical layer according to claim 6, wherein in formula (II)

Mn;

R²¹ is selected from CH₃, C₂H₅, C₃H₇ or unsubstituted phenyl, R²² is selected from CH₃ or C₂H₅, R²³ is selected from H, Cl, CH₃, C₂H₅ or NO₂, R²⁴ is hydrogen, CH₃ or C₂H₅, R²⁵ is selected from unsubstituted phenyl or substituted phenyl, with 1 to 4 substituents independently from each other being selected from the group consisting of halogen, C_1-10 alkyl and nitro.

8. An optical layer according to claim 6 or 7, wherein the compound of formula (II) is represented by formula (II- 1),

wherein MC is selected from the group consisting of Ni, Cu, Co, Zn, Al, Fe, Pd, Pt, Cr and Mn.

9. A method for producing an optical layer according to claim 5, comprising the following steps

(a) providing a substrate

(b) dissolving a compound or a mixture of compounds of formula (I), as defined in anyone of the claims 1 to 4, in an organic solvent to form a solution,

(c) coating the solution (b) on the substrate (a);

(d) evaporating the solvent to form a dye film.

10. A method according to claim 9 for producing an optical layer according to one or more of claims 6 to 8, wherein in step (b) a mixture of one or more of compounds of formula (I), as defined in anyone of the claims 1 to 4, and one or more of compounds of formula (II), as defined in anyone of the claims 6 to 8, is dissolved in an organic solvent to form a solution.

11. A method according to claims 9 or 10, wherein the substrate is selected from polycarbonate (PC) or amorphous polyolefins.

12. A method according to one or more of claims 9 to 11, wherein the organic solvent is selected from C_1-8 alcohol, halogen substituted C_1-8 alcohols, C_1-8 ketone, C_1-8 ether, halogen substituted C_1-4 alkane, or amides.

13. An optical data recording medium comprising an optical layer according to one or more of claims 5 to 8.