Squarylium dyes as light-absorbing compound in the information layer of optical data carriers
Novel squarylium compounds for optical data carriers have been found. The latter comprise a preferably transparent substrate to whose surface a light-writable information layer, if desired one or more reflection layers and a further substrate or a protective layer have been applied and can be written on and read by means of red light, preferably laser light, where the information layer comprises a light-absorbent compound and, if desired, a binder. They are characterized in that at least the said squarylium compounds are used as light-absorbent compound.
1 . Squarylium compounds of the formula I
where
R is a heterocyclic five-membered ring, with the exception of amino-substituted furan rings.
2 . Compounds according to claim, 1, characterized in that R is a substituted or unsubstituted pyrrole.
3 . Compounds according to claim 1 , characterized in that they have the formula Ia
where
R 1 is hydrogen, substituted or unsubstituted alkyl or substituted or unsubstituted aralkyl,
R 2 is substituted or unsubstituted alkyl, substituted or unsubstituted aryl, alkoxycarbonyl or substituted or unsubstituted alkylcarbonyl, and
R 3 and R 4 are each, independently of one another, hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, alkoxycarbonyl or substituted or unsubstituted alkylcarbonyl.
4 . Compounds according to claim 3 , characterized in that
R 1 is hydrogen, methyl, ethyl, propyl, butyl, cyclohexylmethyl, benzyl, 4-methoxybenzyl, 4-trifluoromethylbenzyl, 3-trifluoromethylbenzyl, 2-trifluoromethylbenzyl, 3,5-bis(trifluoromethyl)benzyl or 4-fluoro-2-trifluoromethylbenzyl,
R 2 is methyl, ethyl, propyl or phenyl and
R 3 and R 4 are each, independently of one another, hydrogen, methyl, ethyl propyl, butyl, phenyl, acetyl or ethoxycarbonyl.
5 . Compounds according to claim 3 , characterized in that
R 1 is 4-trifluoromethylbenzyl or 3,5-bis(trifluoromethyl)benzyl, in particular 4-trifluoromethylbenzyl,
R 2 is methyl, ethyl or phenyl, in particular methyl,
R 3 is hydrogen, ethyl, acetyl or ethoxycarbonyl, in particular ethyl, and
R 4 is methyl, ethyl or phenyl, in particular methyl or ethyl.
6 . Process for preparing the squarylium compounds according to claim 1 , which is characterized in that 3,4-dihydroxy-3-cyclobutene-1,2-dione (squaric acid) is reacted with at least one compound of the formula III
R—R 5 (III),
in particular with a pyrrole compound of the formula (IIIa),
where
R 5 is hydrogen, ethoxycarbonyl or carboxyl and
R 1 to R 4 are as defined above.
7 . Use of squarylium compounds according to claim 1 as light-absorbent compounds in the information layer of write-once optical data carriers.
8 . Use according to claim 7 , characterized in that the optical data carrier can be written and read by means of red laser light, in particular having a wavelength in the range 600-680 nm.
9 . Pyrroles of the formula (IIIa)
where
R 1 is substituted or unsubstituted C 3 -C 12 -alkyl or substituted or unsubstituted aralkyl,
R 2 is substituted or unsubstituted alkyl, substituted or unsubstituted aryl, alkoxycarbonyl, carbonyl or substituted or unsubstituted alkylcarbonyl,
R 3 and R 4 are each, independently of one another, hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, alkoxycarbonyl, carbonyl or substituted or unsubstituted alkoxycarbonyl and
R 5 is hydrogen, alkoxycarbonyl or carboxyl.
10 . Pyrrole compounds according to claim 9 , characterized in that
R 1 is propyl, butyl, cyclohexylmethyl, benzyl, 4-methoxybenzyl, 4-trifluoromethylbenzyl, 3-trifluoromethylbenzyl, 2-trifluoromethylbenzyl, 3,5-bis(trifluoromethyl)benzyl or 4-fluoro-2-trifluoromethylbenzyl,
R 2 is methyl, ethyl, propyl or phenyl,
R 3 and R 4 are, independently of one another, hydrogen, methyl, ethyl, propyl, butyl, phenyl, acetyl or ethoxycarbonyl and
R 5 is hydrogen, t-butoxycarbonyl or carboxyl.
11 . Process for preparing pyrroles of the formula (11a) according to claim 9 , characterized in that a pyrrole compound of the formula (II)
where
R 2 to R 4 are as defined in claim 9 for the pyrroles of the formula IIIa and
R 5 is hydrogen, alkoxycarbonyl, in particular t-butoxycarbonyl or ethoxycarbonyl, or carboxyl,
is reacted with a halogen compound of the formula IV
R 1 —X (IV),
where
R 1 is as defined in claim 9 for the pyrroles of the formula IIIa,
X is Cl, Br or 1,
and at least 2 equivalents of a base.
12 . Optical data carrier comprising a preferably transparent substrate to whose surface a light-writable information layer, if desired one or more reflection layers and a further substrate or a protective layer have been applied, which can be written on or read by means of red light, preferably laser light, where the information layer comprises a light-absorbent compound, characterized in that at least one squarylium compound according to at least one of claims 1 to 5 is used as light-absorbent compound.
13 . Process for producing the optical data carriers according to claim 12 , which is characterized in that a preferably transparent substrate is coated with squarylium compounds according to claim 1 , if desired in combination with suitable binders and additives and if desired suitable solvents and is, if desired, provided with a reflection layer, further intermediate layers and, if desired, a protective layer or a further substrate.
14 . Optical data carriers according to claim 12 which have been written on by means of red light, in particular red laser light.
15 . Optical data carrier comprising a preferably transparent substrate which may, if desired, have previously been coated with one or more reflection layers and to whose surface a light-writable information layer, if desired one or more reflection layers and if desired a protective layer or a further substrate or a covering layer have been applied, which can be written on or read by means of blue light, preferably laser light, particularly preferably light having a wavelength of 360-460 nm, in particular 380-420 nm, very particularly preferably 390-410 nm, or by means of infrared light, preferably laser light, particularly preferably light having a wavelength of 760-830 nm, where the information layer comprises a light-absorbent compound and, if desired, a binder, characterized in that at least one phthalocyanine of the formula (I)
where
Me is a doubly axially substituted metal atom from the group consisting of Si, Ge and Sn,
Pc is an unsubstituted phthalocyanine and
X 1 and X 2 are each, independently of one another, bromine or iodine and X 1 may also be chlorine,
is used as light-absorbent compound.
16 . Optical data store according to claim 1 , characterized in that at least one phthalocyanine of the formulae (Ia), (Ib), (Ic), (Id), (Ie), (If), (Ig) and (Ih)
is used as light-absorbent compound.
17 . Use of phthalocyanines of the formula (I)
where
Me is a doubly axially substituted metal atom from the group consisting of Si, Ge and Sn,
Pc is an unsubstituted phthalocyanine and
X 1 and X 2 are each, independently of one another, bromine or iodine and X 1 may also be chlorine,
as light-absorbent compound in the information layer of optical storage media.
18 . Use of phthalocyanines
where
Me is a doubly axially substituted metal atom from the group consisting of Si, Ge and Sn,
Pc is an unsubstituted phthalocyanine and
X 1 and X 2 are each, independently of one another, bromine or iodine and X 1 may also be chlorine,
for producing optical storage media.
19 . Use according to claim 17 , characterized in that the phthalocyanines used have a purity of more than 90% by weight, in particular more than 95% by weight, particularly preferably more than 98% by weight, based on the phthalocyanine of the formula (I).
20 . Process for coating substrates with the phthalocyanines of the formula (I)
where
Me is a doubly axially substituted metal atom from the group consisting of Si, Ge and Sn,
Pc is an unsubstituted phthalocyanine and
X 1 and X 2 are each, independently of one another, bromine or iodine and X 1 may also be chlorine.
21 . Optical data carriers according to claim 15 which have been written on by means of blue light, in particular laser light, particularly preferably laser light having a wavelength of 360-460 nm.