Patent Application
20060159882
The invention relates to new optical recording materials that have excellent recording and playback quality especially at a wavelength of 350-500 nm. Recording and playback can be effected very advantageously with high sensitivity at the same wavelength, and the storage density that is achievable is significantly higher than in the case of known materials. In addition, the materials according to the invention have very good storage properties before and after recording, even under especially harsh conditions, such as exposure to sunlight or fluorescent lighting, heat and/or high humidity. In addition, their manufacture is simple and readily reproducible using customary coating processes, such as spin-coating.
WO 02/082438 discloses the use of ionic salts, including those with metal complex anions, for optical recording materials. Those colorants are always substituted by alkyl, alkenyl, aryl or heteroaryl at the nitrogen atom. Their optical properties do not, however, fully satisfy increased demands. In particular, the refractive index as well as the absorption and the steepness of the absorption band on its long wavelength flank in the solid still leave something to be desired.
JP-A-11/34500, JP-A-11/92479 and EP-A-0 903 733 disclose metal and boron complexes of colorants of formulae
which can be used at from 520 to 690 nm for optical recording materials such as CD-R or DVD-RF Here too, however, the optical properties, especially the spectral properties in or near the UV range that are necessary for the highest possible storage densities, and the information density per unit surface area are not able to satisfy the highest demands as desired. The information density per unit surface area is far lower than is desirable.
Conventional optical recording materials therefore satisfy high demands only to some extent, or do not satisfy all demands to an entirely satisfactory degree at the same time.
On the other hand, J. Org. Chem. 67/16, 5753-5772 [2002] describes the synthesis of a number of bis(o-azaheteroaryl)methanes and their coordination properties with respect to divalent transition metals, heteroaryl being 1,3-azol-2-yl, 1,3-benzazol-2-yl and azinyl and the transition metals being Zn, Cu, Co, Ni, Hg and Pd. Inter alia 2:1 salt complexes of bis(benzothiazol-2-yl)methane and bis(benzoxazol-2-yl)methane with copper(II) chloride and nickel(II) sulfate, and cobalt(II) chloride and palladium(II) nitrate are disclosed, whereas bis(thiazol-2-yl)methane yields, with deprotonation, neutral 2:1 chelates with Zn(II), Cu(II), Ni(II) and Co(II). All substances are strongly coloured.
The aim of the invention is an optical recording medium having high information density, sensitivity and data reliability. Such a recording medium should be robust, durable and easy to use. Furthermore, it should be inexpensive to manufacture as a mass-produced product and should require equipment that is as small and inexpensive as possible.
The invention therefore relates to an optical recording medium comprising a substrate, a recording layer and optionally one or more reflecting layers, wherein the recording layer comprises a compound of formula
or a tautomer thereof, wherein
G1 and G2 are each independently of the other
A1 and A2 are each independently of the other N(R12), O, S or Se and A3 is C(C1-C5alkyl)2, C(C4-C5alkylene), N(R12), O, S, Se, N═C(R13) or unsubstituted or R14-substituted CH═CH;
M1 is a transition metal of groups IX to XII, preferably Co, Cu, Ni, Pd or Zn, especially Co, Cu or Ni;
Q1 and Q2 are each independently of the other C(R15), N or P;
R1, R2, R3, R4, R5, R6, R7, R8 and R14 are each independently of the others hydrogen, R18, or C6-C12aryl, C4-C12heteroaryl, C7-C12aralkyl or C5-C12heteroaralkyl each unsubstituted or substituted by one or more, where applicable identical or different, radicals R18; or
R1 and R2, R3 and R4, R5 and R6, R5 and R13 and/or R5 and R14, together in pairs, are C3-C6alkylene or C3-C6alkenylene, each of which is unsubstituted or substituted by one or more, where applicable identical or different, radicals R17 and may be uninterrupted or interrupted by O, S or N(R12), or 1,4-buta-1,3-dienylene,
each of which is unsubstituted or substituted by one or more, where applicable identical or different, radicals R18 and in which 1 or 2 carbon atoms may have been replaced by nitrogen;
R9, R12 and R13 are each independently of the others C1-C24alkyl, C3-C24cycloalkyl, C2-C24alkenyl, C3-C24cycloalkenyl, C1-C4alkyl[O—C1-C4alkylene]m or C1-C4alkyl-[NH—C1-C4alkylene]m, each of which is unsubstituted or substituted by one or more, where applicable identical or different, radicals R17; or C6-C12aryl, C4-C12heteroaryl, C7-C12aralkyl or C5-C12heteroaralkyl, each of which is unsubstituted or substituted by one or more, where applicable identical or different, radicals R18;
R10, R11 and R18 are each independently of the others halogen, nitro, cyano, thiocyanato, hydroxy, O—R19, O—CO—R19, S—R19, CHO, COR20, CHOR19OR23, CR20OR19OR23, R18, N═N—R16 , N═CR19R20, N═CR21R22, C(R15═NR19, C(R15)═NR21, C(R15)═CR21R22, NH2, NH—R19, NR19R20, NH3+, NH2R19+, NHR19R20+, NR19R20R23+, CONH2, CONHR19, CONR19R20, SO2R19, SO2NH2, SO2NHR19, SO2NR19R20, COOH, COOR19, OCOOR19, NHCOR19, NR19COR23, NHCOOR19, NR19COOR23, ureido, NR19—CO—NHR23, B(OH)2, B(OH)(OR19), B(OR19)OR23, phosphato, PR19R23, POR19OR23, P(═O)OR19OR23, OPR19R23, OPR19OR23, OP(═O)R19OR23, OP(═O)OR19OR23, OPO3R19, sulfato, sulfo, or C1-C12alkyl, C3-C12cycloalkyl, C1-C12alkylthio, C3-C12cycloalkylthio, C1-C12alkoxy or C3-C12cycloalkoxy each unsubstituted or substituted by one or more, where applicable identical or different, radicals R17;
R15 is hydrogen, cyano, hydroxy, C1-C12alkoxy, C3-C12cycloalkoxy, C1-C12alkylthio, C3-C12cycloalkylthio, amino, NHR24, NR25R26, R27, halogen, nitro, formyl, N═N—R27, C(R14)═CR21R22, C(R14)═NR19, COO—R25, carboxy, carbamoyl, CONH—R25, CONR25R26, N═CR19R20, or C1-C12alkyl, C3-C12cycloalkyl, C2-C12alkenyl or C3-C12cycloalkenyl each unsubstituted or substituted by one or more, where applicable identical or different, halogen, hydroxy, C1-C12alkoxy or C3-C12cycloalkoxy radicals;
R16 is C6-C12aryl, C4-C12heteroaryl, C7-C12aralkyl or C5-C12heteroaralkyl, each of which is unsubstituted or substituted by one or more, where applicable identical or different, radicals R28;
R17 is halogen, hydroxy, O—R25, O—CO—R25, S—R25, NH2, NH—R25, NR25R26, NH3+, NH2R25+, NHR25R26+, NR24R25R26+, NR25—CO—R24, NR25COOR24, cyano, formyl, COO—R25, carboxy, carbamoyl, CONH—R25, CONR25R26, ureido, NH—CO—NHR24, NR25—CO—NHR24, phosphato, PR25R24, POR25OR24, P(═O)OR25OR24, OPR25R24, OPR25OR24, OP(═O)R25OR24, OPO3R25, OP(═O)OR25OR24, SO2R25, sulfato, sulfo, R27, N═N—R27, or C1-C12alkoxy or C1-C12cycloalkoxy each unsubstituted or mono- or poly-substituted by halogen;
R19, R20 and R23 are each independently of the others R16, or C1-C12alkyl, C3-C12cycloalkyl, C2-C12alkenyl or C3-C12cycloalkenyl each unsubstituted or substituted by one or more, where applicable identical or different, halogen, hydroxy, C1-C12alkoxy or C3-C12cycloalkoxy radicals; or
R14 and R19 together, R15 and R19 together and/or R19 and R23 together are C2-C12alkylene, C3-C12cycloalkylene, C2-C12alkenylene or C3-C12cycloalkenylene, each of which is unsubstituted or substituted by one or more, where applicable identical or different, halogen, hydroxy, C1-C12alkoxy or C3-C12cycloalkoxy radicals; or
R19 and R20 together with the common nitrogen are pyrrolidine, piperidine, piperazine or morpholine, each of which is unsubstituted or mono- to tetra-substituted by C1-C4alkyl; or carbazole, phenoxazine or phenothiazine, each of which is unsubstituted or substituted by one or more, where applicable identical or different, radicals R26;
R21 and R22 are each independently of the other NR25R26, CN, CONH2, CONHR19, CONR19R20 or COOR20;
R24, R25 and R26 are each independently of the others C1-C12alkyl, C3-C12cycloalkyl, C2-C12alkenyl, C3-C12cycloalkenyl, C6-C12aryl, C4-C12heteroaryl, C7-C12aralkyl or C5-C12heteroaralkyl; or
R25 and R28 together with the common nitrogen are pyrrolidine, piperidine, piperazine or morpholine, each of which is unsubstituted or mono- to tetra-substituted by C1-C4alkyl;
R27 is C6-C12aryl, C4-C12heteroaryl, C7-C12aralkyl or C5-C12heteroaralkyl, each of which is unsubstituted or substituted by one or more, where applicable identical or different, radicals R18;
R28 is nitro, SO2NHR25, SO2NR25R26, or C1-C12alkyl, C3-C12cycloalkyl, C1-C12alkylthio, C3-C12cycloalkylthio, C1-C12alkoxy or C3-C12cycloalkoxy each unsubstituted or substituted by one or more, where applicable identical or different, radicals R17; and
m is a number from 1 to 10.
When R5 forms a bridge with R6, R5 may not at the same time form a bridge with R13 or R14.
It will be understood that acidic groups, such as carboxy, sulfo, sulfato and phosphate, may also be in the form of a salt, for example an alkali metal, alkaline earth metal, ammonium or phosphonium salt, such as Li+, Na+, K+, Mg2+, Ca2+, Cu2+, Ni2+, Fe2+, Co2+, Zn2+, Sn2+, La3+, ammonium, methylammonium, ethylammonium, isopropylammonium, ™Primene 81-R, ™Rosin Amine D, pentadecylammonium, ™Primene JM-T, dicyclohexylammonium, tetramethylammonium, tetraethylammonium, tetrabutylammonium, benzyltrimethylammonium, benzyltriethylammonium, methyltrioctylammonium, tridodecylmethylammonium, tetrabutylphosphonium, tetraphenylphosphonium, butyltriphenylphosphonium or ethyltriphenylphosphonium, or any of the cations B-1 to B-169 mentioned in U.S. Pat. No. 6,225,024, to which individually reference is expressly made here.
Halogen is chlorine, bromine, fluorine or iodine, preferably fluorine or chlorine, especially fluorine on alkyl (for example trifluoromethyl, α,α,α-btrifluoroethyl or perfluorinated alkyl groups, such as heptafluoropropyl) and chlorine on aryl, heteroaryl or on the aryl moiety of aralkyl or on the heteroaryl moiety of heteroaralkyl.
Alkyl, cycloalkyl, alkenyl or cycloalkenyl can be straight-chain or branched, or monocyclic or polycyclic. Alkyl is, for example, methyl, straight-chain C2-C24alkyl or preferably branched C3-C24alkyl. Alkenyl is, for example, straight-chain C2C20alkenyl or preferably branched C3-C24alkenyl. The invention therefore relates especially also to compounds of formula (I) containing branched C3-C24alkyl or branched C3-C24alkenyl, and also to optical recording materials comprising such compounds. C1-C24Alkyl is therefore, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, 2-pentyl, 3-pentyl, 2,2-dimethylpropyl, n-hexyl, n-octyl, 1,1,3,3-tetramethylbutyl, 2-ethylhexyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, elcosyl, heneicosyl, docosyl or tetracosyl. C3-C24Cycloalkyl is, for example, cyclopropyl, cydobutyl, cyclopentyl, cyclohexyl, trimethylcyclohexyl, menthyl, thujyl, bornyl, 1-adamantyl or 2-adamantyl.
C2-C20Alkenyl and C3-C20cycloalkenyl are C2-C20alkyl and C3-C20cycloalkyl that is mono- or poly-unsaturated, wherein two or more double bonds may be isolated or conjugated, for example vinyl, allyl, 2-propen-2-yl, 2-buten-1-yl, 3-buten-1-yl, 1,3-butadien-2-yl, 2-cyclobuten-1-yl, 2-penten-1-yl, 3-penten-2-yl, 2-methyl-1-buten-3-yl, 2-methyl-3-buten-2-yl, 3-methyl-2-buten-1 -yl, 1,4pentadien-3-yl, 2-cyclopenten-1-yl, 2-cyclohexen-1-yl, 3-cyclohexen-1-yl, 2,4-cyohexadien-1-yl, 1-p-menthen-8-yl, 4(10)-thuien-10-yl, 2-horbornen-1-yl, 2,5-norbornadien-1-yl, 7,7dimethyl-2,4-norcaradien-3yl or the various isomers of hexenyl, octenyl, nonenyl, decenyl, dodecenyl, tetradecenyl, hexadecenyl, octadecenyl, eicosenyl, henelcosenyl, docosenyl, tetracosenyl, hexadienyl, octadienyl, nonadienyl, decadienyl, dodecadienyl, tetradecadienyl, hexadecadienyl, octadecadienyl or eicosadienyl.
C7-C12Aalkyl is, for example, benzyl, 2-benzyl-2-propyl, β-phenyethyl, 9-fluorenyl, α,α-dimethylbenzyl, ω-henyl-butyl or ω-phenyl-hexyl. When C7-C12aralkyl is substituted, both the alkyl moiety and the aryl moiety of the aralkyl group can be substituted, the latter alternative being preferred.
C6-C12Aryl is, for example, phenyl, naphthyl, biphenylyl or 2-fluorenyl.
C4-C12Heteroaryl is an unsaturated or aromatic radical having 4n+2 conjugated π-electrons, for example 2-thienyl, 2-furyl, 2-pyridyl, 2-thiazolyl, 2-oxazolyl, 2-imidazolyl, isothiazolyl, triazolyl or any other ring system consisting of thiophene, furan, pyridine, thiazole, oxazole, imidazole, isothiazole, triazole, pyridine and benzene rings and unsubstituted or substituted by from 1 to 6 ethyl, methyl, ethylene and/or methylene substituents, for example benzotriazolyl, and in the case of N-heterocycles where applicable also those in the form of their N-oxides.
C5-C12Heteroaralkyl is, for example, C1-C8alkyl substituted by C4-C11heteroaryl.
Furthermore, aryl and aralkyl can also be aromatic groups bonded to a metal, for example in the form of metallocenes of transition metals known per se, more especially
The transition metal M1 is preferably in the form of a doubly positively charged cation, for example Co2+, Cu2+, Ni2+, Pd2+ or Zn2+, especially Co2+, Cu2+ or Ni2+.
The compound of formula (I) may also be a cation which has been neutralised with an inorganic, organic or organometallic anion, for example when one or more ammonium groups are present or when the transition metal has one or more excess positive charges, such as in Co3+. The inorganic, organic or organometallic anion may be, for example, the anion of a mineral acid, of the conjugated base of an organic acid (for example an alcoholate, phenolate, carboxylate, sulfonate or phosphonate) or an organometallic complex anion, for example fluoride, chloride, bromide, iodide, perchlorate, periodate, nitrate, hydrogen carbonate, ½ carbonate, ½ sulfate, C1-C4alkyl sulfate, hydrogen sulfate, ⅓ phosphate, ½ hydrogen phosphate, dihydrogen phosphate, ½ C1-C4alkanephosphonate, C1-C4alkane-C1-C12alkylphosphonate, di-C1-C4alkylphosphinate, tetrafluoroborate, hexafluorophosphate, hexafluoroantimonate, acetate, trifluoroacetate, heptafluorobutyrate, ½ oxalate, methanesulfbnate, trifluoromethanesulfonate, benzenesulfonate, tosylate, p-chlorobenzenesulfonate, p-nitrobenzenesulfonate, phenolate, benzoate or a negatively charged metal complex.
The person skilled in the art will readily recognise that it is also possible to use other anions with which he is familiar. It will be self-evident to him that
of an inorganic, organic or organometallic anion having x negative charges, for example ½.SO42−, is a multiply charged anion which neutralises several singly charged cations or a cation having x charges, as the case may be.
Phenolates or carboxylates are, for example, of formula
(wherein R29, R30 and R31 are each independently of the others hydrogen, R18, or C6-C12aryl, C4-C12heteroaryl, C7-C12aralkyl or C5-C12heteroarylalkyl each unsubstituted or substituted by one or more, where applicable identical or different, radicals R18, for example anions of C1-C12alkylated, especially tert-C4-C8alkylated, phenols and benzoic acids, such as
Preference is given to compounds of formula (I) wherein
A1, A2 and A3 are each independently of the others O, S or N(R12) and/or Q1 and Q2 are C(R15) or N;
G1 and G2 are each independently of the other
R1, R2, R3, R4, R5, R6, R7, R8 and R14 are each independently of the others hydrogen, R18, or C6-C12aryl or C7-C12aralkyl each unsubstituted or substituted by one or more, where applicable identical or different, radicals R18;
R9, R12 and R13 are each independently of the others unsubstituted or R17-substituted C1-C8alkyl;
R10 and R18 are each independently of the other halogen, nitro, cyano, O—R19, formyl, CH═C(CN)2, CH═C(CN)CONH2, CH═C(CN)CONHR19, CH═C(CN)CONR19R20, CH═C(CN)COOR19, CH═C(COOR19)COOR20, CONH2, CONHR19, CONR19R20, SO2C1-C12alkyl, SO2NH2, SO2NHR19, SO2NR19R20, COOH, COOR19, NHCOR19, NR19COR23, NHCOOR19, NR19COOR23, ureido, P(═O)OR19OR23, sulfo, or C1-C12alkyl, C1-C12alkylthio or C1-C12alkoxy each unsubstituted or substituted by one or more, where applicable identical or different, radicals R17;
R15 is hydrogen, cyano, halogen, nitro, formyl, N═N—R27, C(R14)═CR21R22, C(R14)═NR19, COO—R25, carboxy, carbamoyl, CONH—R25, CONR25R26, or C1-C12alkyl unsubstituted or substituted by one or more halogen substituents;
R16 is unsubstituted or substituted C6-C12aryl or C7-C12aralkyl, especially a metallocenyl radical;
R17 is halogen, hydroxy, O—R25, amino, NH—R25, NR25R26, NR25—CO—R24, NR25COOR24, cyano, COO—R25, carboxy, CONH—R25, CONR25R26, sulfato, sulfo, or C1-C12alkoxy unsubstituted or mono- or poly-substituted by halogen;
R19, R20 and R23 are each independently of the others C1-C12alkyl unsubstituted or substituted by one or more, where applicable identical or different, halogen, hydroxy or C1-C12alkoxy radicals% or unsubstituted C6-C12aryl or C7-C12aralkyl; or
R19 and R20 together with the common nitrogen are morpholine, or piperidine N-substituted by C1-C4alkyl;
R25, R26 and R24 are each independently of the others C1-C12alkyl, C2-C12alkenyl, C8-C12aryl or C7-C12aralkyl; or
R25 and R26 together with the common nitrogen are morpholine, or piperidine N-substituted by C1-C4alkyl; and/or
m is a number from 1 to 4.
Special preference is given to compounds of formula (I) wherein Q1 and Q2 are C(R15); G1 and G2 are
and A1, A2 and A3 are O, S or N(R12);
R12 is C1-C24allyl, C1-C4alkyl-[O—C1-C4alkylene]m or C1-C4alkyl-[NH—C1-C4alkylene]m, each of which is unsubstituted or substituted by one or more, where applicable identical or different, radicals R17, or C6-C12aryl unsubstituted or substituted by one or more, where applicable identical or different, radicals R18;
R15 is hydrogen, cyano, COO—R25 or C1-C12alkyl;
R17 is halogen, hydroxy, O—R25, cyano, COO—R25 or carboxy; and
R18 is halogen, nitro, cyano, O—R19, CH═C(CN)2, COOR19, ureido, CONR25R26, SO2R25, P(═O)OR19OR23 or unsubstituted or substituted C1-C12alkyl.
Those preferred meanings apply both individually and in any combination. The compounds of formula (I) generally exhibit more advantageous properties, the more preferred individual features they have.
Also preferred are compounds of formula (I) wherein
The recording layer advantageously comprises a compound of formula (I) or a mixture of such compounds as main component, for example at least 30% by weight, preferably at least 60% by weight, especially at least 80% by weight Further customary constituents are possible, for example other chromophores (for example those disclosed in WO 01/75873, or others having an absorption maximum at from 300 to 1000 nm), stabilisers, 1O2—, triplet- or luminescence-quenchers, melting-point reducers, decomposition accelerators or any other additives that have already been described in optical recording media. Preferably, stabilisers or fluoresence-quenchers are added if desired.
When the recording layer comprises further chromophores, the amount of such chromophores should preferably be small, so that the absorption thereof at the wavelength of the inversion point of the longest-wavelength flank of the absorption of the entire solid layer is a fraction of the absorption of the pure compound of formula (I) in the entire solid layer at the same wavelength, advantageously at most ⅓, preferably at most ⅕, especially at most 1/10. The absorption maximum is preferably higher than 425 nm, especially higher than 500 nm.
Stabilisers, 1O2—, triplet- or luminescence-quenchers are, for example, metal complexes of N- or S-containing enolates, phenolates, bisphenolates, thiolates or bisthiolates or of azo, azomethine or formazan dyes, such as bis(4-dimethylamino-dithiobenzil)nickel [CAS No 38465-55-3], ®Irgalan Bordeaux EL, ®Cibafast N or similar compounds, hindered phenols and derivatives thereof (optionally also as counter-ions X), such as ®Cibafast AO, o-hydroxyphenyl-triazoles or -triazines or other UV absorbers, such as ®Cibafast W or ®Cibafast P or hindered amines (TEMPO or HALS, also as nitroxides or NOR-HALS, optionally also as counter-ions X), and also as cations diummonium, Paraquat™ or Orthoquat™ salts, such as ®Kayasorb IRG 022, ®Kayasorb IRG 040, optionally also as radical ions, such as N,N,N′,N′-tetrakis(4-dibutylaminophenyl)p-phenyleneamine-ammonium hexafluorophosphate, hexafluoroantimonate or perchlorate. The latter are available from Organica (Wolfen/Del.); ®Kayasorb brands are available from Nippon Kayaku Co. Ltd., and ®Irgalan and ®Cibafast brands are available from Ciba Spezialitätenchemie AG.
Many such structures are known, some of them also in connection with optical recording media, for example from U.S. Pat. No. 5,219,707, JP-A-06/199045, JP-A-07/76169, JP-A-07/262604 or JP-A-2000/272241. They may be, for example, salts of the metal complex anions disclosed above with any desired cations, for example the cations disclosed above, or metal complexes, illustrated, for example, by a compound of formula
The person skilled in the art will know from other optical information media, or will easily identify, which additives in which concentration are particularly well suited to which purpose. Suitable concentrations of additives are, for example, from 0.001 to 1000% by weight preferably from 1 to 50% by weight, based on the recording medium of formula (I).
The optical recording materials according to the invention exhibit excellent spectral properties of the solid amorphous recording layer. The refractive index is extraordinarily high, in some cases even above 2.5. By virtue of an aggregation tendency in the solid that is surprisingly low for such compounds, the absorption band is narrow and intense, the absorption band being especially steep on the long-wavelength side. Crystallites are unexpectedly and very advantageously not formed or are formed only to a negligible extent The reflectivity of the layers in the range of the writing and reading wavelength is very high in the unwritten state.
By virtue of those excellent layer properties it is possible to obtain a rapid optical recording having high sensitivity, high reproducibility and geometrically very precise mark boundaries, the refractive index and the reflectivity changing substantially, which gives a high degree of contrast. The differences in the mark lengths and the interval distances (“jitter”) are very small, which enables a high storage density to be obtained using a relatively thin recording channel with a narrow track spacing (“pitch”). In addition, the recorded data are played back with an astonishingly low error rate, so that error correction requires only a small amount of storage space.
By virtue of the excellent solubility, including in apolar solvents, solutions can be used even in high concentrations without troublesome precipitation, for example during storage, so that problems during spin-coating are largely eliminated. This applies especially to compounds containing branched C3-C8alkyl.
Recording and playback can take place at the same wavelength, therefore advantageously requiring a simple optical system with a single laser source of advantageously from 350 to 500 nm, preferably from 370 to 450 nm. Especially preferred is the UV range from 370 to 390 nm, especially approximately 380 nm, or especially at the edge of the visible range of from 390 to 430 nm, more especially approximately 405±5 nm. In the field of compact, blue or violet laser diodes (such as Nichia GaN 405 nm) with an optical system of high numerical aperture the marks can be so small and the tracks so narrow that up to about 20 to 25 Gb per recording layer is achievable on a 120 mm disc. At 380 nm it is possible to use indium-doped UV-VCSELs (Vertical-Cavity Surface-Emitting Laser), which laser source already exists as a prototype [Jung Han et al., see MRS Internet J. Nitride Semicond. Res. 5S1, W6.2 (2000)].
The invention therefore relates also to a method of recording or playing back data, wherein the data on an optical recording medium according to the invention are recorded or played back at a wavelength of from 350 to 500 nm.
The recording medium is based on the structure of known recording media and is, for example, analogous to those mentioned above. It may be composed, for example, of a transparent substrate, a recording layer comprising at least one of the compounds of formula (I), a reflector layer and a covering layer, the writing and readout being effected through the substrate.
Suitable substrates are, for example, glass, minerals, ceramics and thermosetting and thermoplastic plastics. Preferred supports are glass and homo- or co-polymeric plastics. Suitable plastics are, for example, thermoplastic polycarbonates, polymides, polyesters, polyacrylates and polymethacrylates, polyurethanes, polyolefins, polyvinyl chloride, polyvinylidene fluoride, polyimides, thermosetting polyesters and epoxy resins. Special preference is given to polycarbonate substrates which can be produced, for example, by injection-moulding. The substrate can be in pure form or may comprise customary additives, for example UV absorbers or dyes, as proposed e.g. in JP-A-04/167239 as light stabilisation for the recording layer. In the latter case it may be that in the range of the writing wavelength (emission wavelength of the laser) the dye added to the support substrate has no or at most only very low absorption, preferably up to a maximum of about 20% of the laser light focussed onto the recording layer.
The substrate is advantageously transparent over at least a portion of the range from 350 to 500 nm, so that it is permeable to, for example, at least 80% of the incident light of the writing or readout wavelength. The substrate is advantageously from 10 μm to 2 mm thick, preferably from 100 to 1200 μm thick, especially from 600 to 1100 μm thick, with a preferably spiral guide groove (track) on the coating side, a groove depth of from 10 to 200 nm, preferably from 80 to 150 nm, a groove width of from 100 to 400 nm, preferably from 150 to 250 nm, and a spacing between two turns of from 200 to 600 nm, preferably from 350 to 450 nm. Grooves of different cross-sectional shape are known, for example rectangular, trapezoidal or V-shaped. Analogously to the known CD-R and DVD-R media, the guide groove may additionally undergo a small periodic or quasi-periodic lateral deflection (wobble), so that synchronisation of the speed of rotation and the absolute positioning of the reading head (pick-up) are made possible. Instead of, or in addition to, the deflection, the same function can be performed by markings between adjacent grooves (pre-pits).
The recording medium is applied, for example, by application of a solution by spin-coating, the objective being to produce a layer that is as amorphous as possible, the thickness of which layer is advantageously from 0 to 40 nm, preferably from 1 to 20 nm, especially from 2 to 10 nm, on the surface (“land”) and, depending upon the geometry of the groove, advantageously from 20 to 150 nm, preferably from 50 to 120 nm, especially from 60 to 100 nm, in the groove.
Reflecting materials suitable for the reflector layer include especially metals, which provide good reflection of the laser radiation used for recording and playback, for example the metals of Main Groups III, IV and V and of the Sub-Groups of the Periodic Table of the Elements. Al, In, Sn, Pb, Sb, Bi, Cu, Ag, Au, Zn, Cd, Hg, Sc, Y, La, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt and the lanthanide metals Ce, Pr, Nd, Pm, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb and Lu and alloys thereof are especially suitable. On account of its high reflectivity and ease of production special preference is given to a reflective layer of aluminium, silver, gold or an alloy thereof (for example a white gold alloy), especially aluminium on economic and ecological grounds. The reflector layer is advantageously from 5 to 200 nm thick, preferably from 10 to 100 nm thick, especially from 40 to 60 nm thick, but reflector layers of greater thickness, for example 1 mm thick or even more, are also possible.
Materials suitable for the covering layer include chiefly plastics, which are applied in a thin layer to the reflector layer either directly or with the aid of adhesion promoters. It is advantageous to select mechanically and thermally stable plastics having good surface properties, which can be modified further, for example written on. The plastics may be thermosetting plastics and thermoplastic plastics. Directly applied covering layers are preferably radiation-cured (e.g. using UV radiation) coatings, which are particularly simple and economical to produce. A wide variety of radiation-curable materials are known. Examples of radiation-curable monomers and oligomers are acrylates and methacrylates of diols, triols and tetrols, polyimides of aromatic tetracarboxylic acids and aromatic diamines having C1-C4alkyl groups in at least two ortho-positions of the amino groups, and oligomers with dialkylmaleinimidyl groups, e.g. dimethylmaleinimidyl groups. For covering layers that are applied using adhesion promoters it is preferable to use the same materials as those used for the substrate layer, especially polycarbonates. The adhesion promoters used are preferably likewise radiation-curable monomers and oligomers. Instead of the covering layer applied using an adhesion promoter there may also be used a second substrate comprising a recording and reflector layer, so that the recording medium is playable on both sides. Preference is given to a symmetrical structure, the two parts being joined together at the reflector side by an adhesion promoter directly or by way of an intermediate layer.
In such a structure, the optical properties of the covering layer, or the covering materials, are essentially unimportant per se provided that, where applicable, curing thereof e.g. by UV radiation is achieved. The function of the covering layer is to ensure the mechanical strength of the recording medium as a whole and, if necessary, the mechanical strength of thin reflector layers. If the recording medium is sufficiently robust, for example when a thick reflector layer is present, it is even possible to dispense with the covering layer altogether. The thickness of the covering layer depends upon the thickness of the recording medium as a whole, which should preferably be a maximum of about 2 mm thick The covering layer is preferably from 10 μm to 1 mm thick.
The recording media according to the invention may also have additional layers, for example interference layers or barrier layers. It is also possible to construct recording media having a plurality of (for example from two to ten) recording layers. The structure and the use of such materials are known to the person skilled in the art. Where present, interference layers are preferably arranged between the recording layer and the reflecting layer and/or between the recording layer and the substrate and consist of a dielectric material, for example as described in EP-A-0 353 393 of TiO2, Si3N4, ZnS or silicone resins.
The recording media according to the invention can be produced by processes known per se, it being possible for various methods of coating to be employed depending upon the materials used and their function.
Suitable coating methods are, for example, immersion, pouring, brush-coating, blade-application and spin-coating, as well as vapour-depositon methods carried out under a high vacuum. When, for example, pouring methods are used, solutions in organic solvents are generally employed. When solvents are employed, care should be taken that the supports used are insensitive to those solvents. Suitable coating methods and solvents are described, for example, in EP-A-0 401 791.
The recording layer is applied preferably by the application of a dye solution by spin-coating, solvents that have proved satisfactory being especially alcohols, e.g. 2-methoxyethanol, isopropanol or n-butanol, hydroxyketones, for example diacetone alcohol or 3-hydroxy-3-methyl-2-butanone, hydroxy esters, for example lactic acid methyl ester or isobutyric acid methyl ester, or preferably fluorinated alcohols, for example 2,2,2-trifluoroethanol or 2,2,3,3-tetrafluoro-1-propanol, and mixtures thereof. Further suitable solvents are disclosed, for example, in EP-A-0 483 387.
The application of the metallic reflector layer is preferably effected by sputtering or by vapour-deposition in vacuo. Such techniques are known and are described in specialist literature (e.g. J. L. Vossen and W. Kern, “Thin Film Processes”, Academic Press, 1978). The operation can advantageously be carried out continuously and achieves good reflectivity and a high degree of adhesiveness of the metallic reflector layer.
Recording is carried out in accordance with known methods by writing pits (marks) of fixed or variable length by means of a modulated, focussed laser beam guided at a constant or variable speed over the surface of the recording layer. Readout of information is carried out according to methods known per se by registering the change in reflection using laser radiation, for example as described in “CD-Player and R-DAT Recorder” (Claus Biaesch-Wiepke, Vogel Buchverlag, Würzburg 1992).The person skilled in the art will be familiar with the requirements.
The information-containing medium according to the invention is especially an optical information material of the WORM type. It can be used, for example, analogously to CD-R (compact disc—recordable) or DVD-R (digital video disc—recordable) in computers, and also as storage material for identification and security cards or for the production of diffractive optical elements, for example holograms.
Alternatively, however, there are also recording media which differ substantially from CDR and DVD-R and in which recording and playback take place not through the substrate but through the covering layer (“in-groove recording”). Accordingly the respective roles of the covering layer and the substrate, especially the geometry and the optical properties, are reversed in comparison with the structure described above. Analogous concepts are described a number of times in Proceedings SPIE-Int Soc. Opt Eng. 1999, 3864 for digital video recordings in conjunction with a blue GaN laser diode. For such recording media, which are especially suitable for a high storage density and have correspondingly small marks (“pits”), precise focussing is important, so that the manufacturing process, while essentially analogous, is considerably more awkward.
The compounds of formula (I) according to the invention, however, also meet the increased demands of an inverse layer structure surprisingly well. Preference is therefore given to an inverse layer structure having the layer sequence substrate, reflector layer, recording layer and covering layer. The recording layer is therefore located between the reflector layer and the covering layer. A thin covering layer approximately from 50 to 400 μm in thickness is especially advantageous (typically 100 μm at a numerical aperture of 0.85).
The recording and reflector layers in an inverse layer structure have in principle the same functions as indicated above. As with the groove geometry, they therefore usually have dimensions within the ranges indicated above.
The inverse layer structure requires particularly high standards, which the compounds used according to the invention fulfill astonishingly well, for example when the recording layer is applied to the metallic reflector layer and especially when a covering layer is applied to the recording layer, the covering layer being required to provide the recording layer with adequate protection against rubbing, photooxidation, fingerprints, moisture and other environmental effects and advantageously having a thickness in the range of from 0.01 to 0.5 mm, preferably in the range of from 0.05 to 0.2 mm, especially in the range of from 0.08 to 0.13 mm.
The covering layer preferably consists of a material that exhibits a transmission of 80% or above at the writing or readout wavelength of the laser. Suitable materials for the covering layer include, for example, those materials mentioned above, but especially polycarbonate (such as Pure Ace® or Panlite®, Teijin Ltd), cellulose triacetate (such as Fujitac®, Fuji Photo Film) or polyethylene terephthalate (such as Lumirror®, Toray Industry), special preference being given to polycarbonate. Especially in the case of directly applied covering layers, radiation-cured coatings, such as those already described above, are advantageous, for example SD 347™ (Dainippon Ink).
The covering layer can be applied directly to the solid recording layer by means of a suitable adhesion promoter. In another embodiment, there is applied to the solid recording layer an additional, thin separating layer of a metallic, crosslinked organometallic or preferably dielectric inorganic material, for example in a thickness of from 0.001 to 10 μm, preferably from 0.005 to 1 μm, especially from 0.01 to 0.1 μm, for example from 0.05 to 0.08 μm in the case of dielectric separating layers and from 0.01 to 0.03 μm in the case of metallic separating layers. Separating layers and corresponding methods are disclosed in WO 02/082438, to which reference is expressly made here. If desired, such coatings can be applied, for example, in the same thickness also between the support material and the metallic reflector layer or between the metallic reflector layer and the optical recording layer. This may be advantageous in certain cases, for example when a silver reflector is used in combination with sulfur-containing additives in the recording layer.
In a special variant, there is applied to the solid recording layer an additional, thin separating layer of a metallic, crosslinked organometallic or dielectric inorganic material, for example in a thickness of from 0.001 to 10 μm, preferably from 0.005 to 1 μm, especially from 0.01 to 0.1 μm. On account of their high reflectivity, metallic separating layers should advantageously be a maximum of 0.03 μm thick.
Separating layers and corresponding methods are disclosed in WO 02/082438, to which reference is expressly made here.
Some of the compounds used according to the invention are known, especially from J. Org. Chem. 67/16, 5753-5772 [2002].
It is also possible, however, to prepare analogously to the known compounds new compounds that can be used in accordance with the invention in optical recording media.
The invention therefore relates also to compounds of formula (I), with the exception of the already known compounds of formula M2(Z1)2, wherein:
Reference is made especially to compounds of formulae
and to compounds wherein M2 is Cu, Co, Ni or Pd and Z1 is a radical of the following compounds:
Especially interesting properties are exhibited by the preferred compounds of formulae
also mixtures of compounds of formula (II) and/or (III), wherein especially G1 and G2 are the preferred heterocycles disclosed above and at the same time or independently thereof M1 is a preferred transition metal. A3 in G1 and G2 can be especially N(R12), O, S or, especially in formula (III), C(C1-C5alkyl)2.
Special preference is given to compounds of formula
and mixtures thereof wherein A4, independently of A3, has the same definition and the same preferred meanings as A3.
Very special preference is given to compounds of formula
Both in formula (IV) and in formula (V), R32, R33, R34, R35, R36, R37, R38 and R39 are preferably H, C1-C4alkyl, COO—C1-C4alkyl, CN, NO2, CHO, COC1-C4alkyl, phenyl, CH[—O—C2-C3alkylene-O—], C(C1-C4alkyl)[—O—C2-C3alkylene-O—], CH═C(CN)2, C(CN)═C(CN)2or C(C1-C4alkyl)═C(CN)2, especially H, CH3, C2H5, COOCH3, COOC2H5, CN, NO2 or CHO.
Compounds of formula (IV) are, for example, the following:
Compounds of formula (V) are, for example, the following:
Instead of pure compounds it is also possible to use mixtures thereof, for example the following mixtures:
Instead of preparing mixtures by mixing together the components, it is favourably possible to prepare mixtures by mixed synthesis, the metals being added in any desired order in succession or preferably simultaneously to a pre-prepared mixture of the ligands, or conversely the ligands being added in any desired order in succession or preferably all of them simultaneously to a pre-prepared mixture of the metals. The mixtures prepared by mixed synthesis generally have somewhat better solubility than physical mixtures, possibly because of their asymmetric components.
In addition to comprising one or more compounds of formula (I) and optionally customary additives, the optical recording media according to the invention may also comprise other chromophores, preferably metal-free chromophores. Other chromophores may, if desired, be added in an amount of from 1 to 200% by weight, based on the total of the compounds of formula (I). The amount of other chromophores is preferably from 5 to 100% by weight, especially from 10 to 50% by weight, based on the total of the compounds of formula (I). Chromophores can be dyes or UV absorbers, preferably having an absorption maximum of from 350 to 400 nm or at from 600 to 700 nm, for example around 380 or 630 nm.
Especially preferred additional metal-free chromophores are cyanines, azacyanines, merocyanines and oxonols and also rhodamines, for example those disclosed in WO 04/006878, WO 02/082438 or EP-A-1 083 555, and also
wherein R40 is C1-C24alkyl or C2-C24alkenyl, each of which can be unsubstituted or substituted, and R41 is any substituent R40 may be, for example, methyl, ethyl, vinyl, allyl, isopropyl, n-butyl, 2-isopropyloxyethyl, n-pentyl, 3-methyl-butyl, 3,3-dimethyl-butyl, 2-ethyl-hexyl, 2-cyano-ethyl, furan-2-ylmethyl or 2-hydroxy-methyl; R41 is, for example, C6-C10aryl, C1-C24alkyl or C2-C24alkenyl.
Purely illustrative examples of such chromophores are:
The following Examples illustrate the invention but do not limit the scope thereof (unless otherwise indicated, “%” always refers to % by weight):
1.0 g of the compound of formula
is applied in the form of a dichloromethane solution to glass. The solid layer is irradiated for 90 hours with xenon light according to ISO-105-B02 (Atas Ci-35 Weather-O-meter, 15 kJ/cm2). The light stability is excellent (see Example 7).
On the solid layer according to Example 1, marks are written into the recording layer using a pulsed dye laser (15 ns pulse length) at a wavelength of 405 nm at an energy density of 0.8 kJ/m2. The written sites exhibit a resulting change in reflectivity.
0.5 g of the compound according to Example 1 is dissolved in 99.5 g of dioxane and applied by means of spin-coating to a silicon wafer. The colourless solid layer is measured using a spectral ellipsometer (Sopra). At a wavelength of 405 nm a refractive index of 2.52 is determined.
1.0 g of the compound of formula
dissolved in 99 g of methylcydohexane and filtered through a 0.2 μm Teflon filter. The dye solution is then applied by rotation at 250 rev/min to a 1.2 mm thick, flat polycearbonate plate (diameter 120 mm). The rotational speed is then increased to 1200 rev/min, so that the excess solution is spun off, and a uniform solid layer is formed. After drying, the solid layer has an absorption of 0.61 at 382 nm. Using an optical measuring system (ETA-RT, STEAG ETA-Optk), the layer thickness and the complex refractive index are determined. At 405 nm the dye layer has a layer thickness of 56 nm, a refractive index n of 1.95 and an extinction coefficient k of 0.090.
Synthesis of the Ligand
19.4 ml of a 55% aqueous chloracetaldehyde solution are added to a suspension of 10.2 g of dithiobiuret in 45 ml of ethanol. The reaction mixture is heated at 75° C. for 2 hours, and then poured into 150 ml of water. After the addition of 200 ml of an aqueous sodium acetate solution (4.6N), the precipitate is filtered off, washed with water and dried at 50° C./1.5·103 Pa, yielding 8.8 g of crude product, and after recrystallisation from ethanol 6.7 9 of pure product of formula
(m.p. 212° C.).
Synthesis of the Complex
0.5N aqueous copper(II) acetate solution is added to a solution of 458 mg of the resulting ligand in 30 ml of ethanol until precipitation, which begins immediately, is complete. After filtration, the product is washed with ethanol and diethyl ether, and then dried at 70° C./1.5·103 Pa. 390 mg of pure product of formula
(decomp. 264° C.) are obtained.
1.0 g of the complex according to Example 5 is dissolved in 99 g of 2,2,3,3-tetrafluoro-1-propanol and filtered through a 0.2 μm Teflon filter. The dye solution is then applied by rotation at 250 rev/min to a 1.2 mm thick, flat poly-carbonate plate (diameter 120 mm); the rotational speed is then increased to 1500 rev/min, so that the excess solution is spun off and a uniform solid layer is formed. After drying, the solid layer has an absorption of 0.35 at 356 nm. Using an optical measuring system (ETA-RT, STEAG ETA-Optik), the layer thickness and the complex refractive index are determined. At 405 nm the dye layer has a layer thickness of 18 nm, a refractive index n of 2.25 and an extinction coefficient k of 0.031.
The procedure is analogous to Example 6, but instead of the complex of Example 5 the following ligands and metal cations are used:
The procedure is analogous to Example 6, but instead of the complex of Example 5 the mixtures M1 to M24 are used.
The procedure is analogous to Example 6, but instead of the complex of Example 5 there are used mixtures having the same proportions of metal and ligand as mixtures M1 to M24 but the complexes are prepared by mixed synthesis (variant of the simultaneous addition of the metal mixture to the ligand mixture). The results are similar to those of Examples 39-62, but have surprisingly better solubility and solution stability.
The procedure is analogous to Example 6, but instead of the complex of Example 5 there are used the following mixtures of compounds of formula (I) with cyanines and merocyanines:
It will be understood that it is also possible to combine mixtures of those cyanines, merocyanines and/or also other chromophores with complexes of formula (I) or with mixtures of complexes of formula (I), the results achieved generally being very good.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20030331/03 | Mar 2003 | CH | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP04/50185 | 2/23/2004 | WO | 8/19/2005 |
