Methine dyes based on formylaminopyridones

Methine dyes of the formula ##STR1## where K is a carbocyclic or heterocyclic radical, PA0 X is nitrogen or a radical of the formula C--Q.sup.1, and PA0 Q.sup.1, Q.sup.2 and Q.sup.3 are hydrogen, substituted or unsubstituted C.sub.1 -C.sub.6 -alkyl, C.sub.3 -C.sub.8 -cycloalkyl, substituted or unsubstituted phenyl, C.sub.1 -C.sub.6 -alkoxy, benzyloxy, substituted or unsubstituted phenoxy, C.sub.1 -C.sub.6 -alkylthio, halogen, cyano, formylamino or a radical of the formula R.sup.3, --CO--OR.sup.1, --CO--NHR.sup.1, --CO--NH--CO--R.sup.1, --CO--NH--CO--R.sup.3, --CO--NH--SO.sub.2 R.sup.3, --NH--CO--R.sup.1, --NH--CO--OR.sup.1, --NH--CO--NR.sup.1 R.sup.2, NH--CS--OR.sup.1, --NH--CS--NR.sup.1 R.sup.2, --NH--CO--R.sup.3, --NH--SO.sub.2 --R.sup.1, --NH--SO.sub.2 --R.sup.3 or --NH--SO.sub.2 --NR.sup.1 R.sup.2, wherein R.sup.1 and R.sup.2 are substituted or unsubstituted C.sub.1 -C.sub.13 -alkyl, C.sub.3 -C.sub.8 -cycloalkyl or substituted or unsubstituted phenyl, or else --NR.sup.1 R.sup.2 is amino, and R.sup.3 is a heterocyclic radical, or Q.sup.1 and Q.sup.2 are together with the carbon atoms to which they are attached a carbocyclic or heterocyclic ring, with the proviso that at least one of Q.sup.1, Q.sup.2 or Q.sup.3 is formylamino, are useful in thermal transfer.

CROSS-REFERENCE 
This application is a 371 of PCT/EP95/04651 filed Nov. 25, 1995. 
BACKGROUND OF THE INVENTION 
Field of the Invention 
The present invention relates to novel methine dyes of the formula I 
##STR2## 
where K is a 5- or 6-membered carbocyclic or heterocyclic radical, 
X is nitrogen or a radical of the formula C--Q.sup.1, and 
Q.sup.1, Q.sup.2 and Q.sup.3 are independently of one another hydrogen, 
C.sub.1 -C.sub.6 -alkyl with or without interruption by 1 or 2 oxygen 
atoms in ether function, benzyl, C.sub.3 --C.sub.8 -cycloalkyl, 
substituted or unsubstituted phenyl, C.sub.1 -C.sub.4 -fluoroalkyl, 
C.sub.1 -C.sub.6 -alkoxy, benzyloxy, substituted or unsubstituted phenoxy, 
C.sub.1 -C.sub.6 -alkylthio, halogen, cyano, formylamino or a radical of 
the formula R.sup.3, --CO--OR.sup.1, --CO--NHR.sup.1, 
--CO--NH--CO--R.sup.1, --CO--NH--CO--R.sup.3, --CO--NH--SO.sub.2 
--R.sup.3, --NH--CO--R.sup.1, --NH--CO--OR.sup.1, --NH--CO--NR.sup.1 
R.sup.2, NH--CS--OR.sup.1, --NH--CS--NR.sup.1 R.sup.2, --NH--CO--R.sup.3, 
--NH--SO.sub.2 --R.sup.1, --NH--SO.sub.2 --R.sup.3 or --NH--SO.sub.2 
--NR.sup.1 R.sup.2, wherein R.sup.1 and R.sup.2 are independently of each 
other C.sub.1 -C.sub.13 -alkyl with or without substitution and with or 
without interruption by from 1 to 3 oxygen atoms in ether function, 
C.sub.3 -C.sub.8 -cycloalkyl or substituted or unsubstituted phenyl, or 
else --NR.sup.1 R.sup.2 is amino, and R.sup.3 is a 5- or 6-membered 
aromatic heterocyclic radical with or without benzofusion and with one or 
more hetero atoms selected from the group consisting of nitrogen, oxygen 
and sulfur, or Q.sup.1 and Q.sup.2 are together with the carbon atoms to 
which they are attached a 5- or 6-membered carbocyclic or heterocyclic 
ring, 
with the proviso that at least one of Q.sup.1, Q.sup.2 or Q.sup.3 is 
formylamino, and to a process for their thermal transfer. 
DESCRIPTION OF THE BACKGROUND 
U.S. Pat. No. 5,310,942 discloses the thermal transfer of pyridone dyes. 
However, it has been found that the dyes used there still have application 
defects. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide novel methine dyes 
which are advantageously useful for non-impact printing processes, for 
example for thermal transfer, and in this use show in particular high 
thermal stability, high light fastness, high color strength and high 
brilliance. The novel dyes should also be advantageous for dyeing or 
printing textile materials. 
We have found that this object is achieved by the above-defined methine 
dyes of the formula I.

DETAILED DESCRIPTION OF THE INVENTION 
K is a 5- or 6-membered carbocyclic or heterocyclic, preferably aromatic, 
radical which may be substituted and may be benzofused. 
K can be derived for example from components of the benzene, indole, 
quinoline, naphthalene, pyrrole, thiazole, benzimidazole, benzothiazole, 
thiophene or pyridine series. 
Important radicals K are for example those of the formulae IIa to IIj 
##STR3## 
where n is 0 or 1, 
Z.sup.1 is hydrogen, C.sub.1 -C.sub.6 -alkyl with or without interruption 
by 1 or 2 oxygen atoms in ether function, hydroxyl, C.sub.1 -C.sub.6 
-alkoxy, C.sub.1 -C.sub.6 -alkylsulfonylamino, mono- or di(C.sub.1 
--C.sub.6 -alkyl)aminosulfonylamino or the radical --NHCOZ.sup.7 or 
--NHCO.sub.2 Z.sup.7, wherein Z.sup.7 is phenyl, benzyl, tolyl or C.sub.1 
-C.sub.6 -alkyl with or without interruption by an oxygen atom in ether 
function, 
Z.sup.2 is hydrogen, halogen, C.sub.1 -C.sub.6 -alkyl or C.sub.1 -C.sub.6 
-alkoxy, 
Z.sup.3 and Z.sup.4 are independently of each other hydrogen, C.sub.1 
-C.sub.13 -alkyl with or without substitution and with or without 
interruption by from 1 to 3 oxygen atoms in ether function, C.sub.3 
-C.sub.4 -alkenyl, C.sub.3 -C.sub.8 -cycloalkyl, phenyl or tolyl or are 
together with the nitrogen atom joining them together a 5- or 6-membered 
saturated heterocyclic radical with or without further hetero atoms, 
Z.sup.5 is hydrogen or C.sub.1 -C.sub.6 -alkyl, and 
Z.sup.6 is hydrogen, halogen, C.sub.1 -C.sub.6 -alkyl, substituted or, 
unsubstituted phenyl, substituted or unsubstituted benzyl, C.sub.3 
-C.sub.8 -cycloalkyl, thienyl, hydroxyl, C.sub.1 -C.sub.6 -alkoxy, C.sub.1 
-C.sub.6 -alkylthio or C.sub.1 -C.sub.6 -monoalkylamino. 
Any alkyl or alkenyl appearing in the abovementioned formulae may be 
straight-chain or branched. 
Any substituted alkyl appearing in the abovementioned formulae may have as 
substituents for example, unless otherwise stated, cyclohexyl, substituted 
or unsubstituted phenyl, C.sub.1 -C.sub.8 -alkanoyloxy, C.sub.1 -C.sub.8 
-alkylaminocarbonyloxy, C.sub.1 -C.sub.8 -alkoxycarbonyl, C.sub.1 -C.sub.8 
-alkoxycarbonyloxy, the alkyl chain of the last three being optionally 
interrupted by from 1 to 3 oxygen atoms in ether function and being 
optionally phenyl- or phenoxy-substsituted, cyclohexyloxy, phenoxy, 
halogen, hydroxyl, carboxyl or cyano. The number of substituents in 
substituted alkyl is generally 1 or 2. 
Any oxygen-interrupted alkyl appearing in the abovementioned formulae is 
preferably interrupted by 1 or 2 oxygen atoms in ether function. 
Any substituted phenyl appearing in the abovementioned formulae may have as 
substituents for example C.sub.1 -C.sub.8 -alkyl, C.sub.1 -C.sub.8 
-alkoxy, halogen, in particular chlorine or bromine, nitro or carboxyl. 
The number of substituents in substituted phenyl is generally from 1 to 3. 
Q.sup.1, Q.sup.2, Q.sup.3, R.sup.1, R.sup.2, Z.sup.1, Z.sup.2, Z.sup.3, 
Z.sup.4, Z.sup.5, Z.sup.6 and Z.sup.7 are each for example methyl, ethyl, 
propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, 
isopentyl, neopentyl, tert-pentyl, hexyl or 2-methylpentyl. 
R.sup.1, R.sup.2, Z.sup.3 and Z.sup.4 may each also be for example heptyl, 
octyl, 2-ethylhexyl, isooctyl, nonyl, isononyl, decyl, isodecyl, undecyl, 
dodecyl, tridecyl, isotridecyl the designations isooctyl, isononyl, 
isodecyl and isotridecyl are trivial names derived from the oxo process 
alcohols (cf. Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, 
Vol. A1, pages 290 to 293, and also Vol. A 10, pages 284 and 285)!. 
Q.sup.1, Q.sup.2, Q.sup.3, R.sup.1, R.sup.2, Z.sup.1, Z.sup.3, Z.sup.4, and 
Z.sup.7 may each also be for example 2-methoxyethyl, 2-ethoxyethyl, 
2-propoxyethyl, 2-butoxyethyl, 2- or 3-methoxypropyl, 2- or 
3-ethoxypropyl, 2- or 3-propoxypropyl, 2- or 4-methoxybutyl or 2- or 
4-ethoxybutyl, 3,6-dioxaheptyl, 3,6-dioxaoctyl, 3,7-dioxaoctyl or 
4,7-dioxaoctyl. 
R.sup.1, R.sup.2, Z.sup.3 and Z.sup.4 may each also be for example 2- or 
3-butoxypropyl, 2- or 4-butoxybutyl, 4,8-dioxanonyl, 3,7-dioxanonyl, 
4,7-dioxanonyl, 4,8-dioxadecyl, 3,6,9-trioxadecyl or 3,6,9-trioxaundecyl. 
Q.sup.1, Q.sup.2, Q.sup.3, Z.sup.1, Z.sup.2 and Z.sup.6 may each also be 
for example methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, 
sec-butoxy, pentyl, isopentyloxy, neopentyloxy or hexyloxy. 
Q.sup.1, Q.sup.2, Q.sup.3, R.sup.1, R.sup.2 and Z.sup.6 may each also be 
for example phenyl, 2-, 3- or 4-methylphenyl, 2-, 3- or 4-ethylphenyl, 2-, 
3- or 4-propylphenyl, 2-, 3- or 4-isopropylphenyl, 2-, 3- or 
4-butylphenyl, 2,4-dimethylphenyl, 2-, 3- or 4-methoxyphenyl, 2-, 3- or 
4-ethoxyphenyl, 2-, 3- or 4-isobutoxyphenyl, 2,4-dimethoxyphenyl, 2-, 3- 
or 4-chlorophenyl, 2,6-dichlorophenyl, 2-, 3- or 4-nitrophenyl or 2-, 3- 
or 4-carboxylphenyl. 
Q.sup.1, Q.sup.2, Q.sup.3, Z.sup.3, Z.sup.4 and Z.sup.6 may each also be 
for example cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl 
or cyclooctyl. 
R.sup.1, R.sup.2, Z.sup.3 and Z.sup.4 may each also be for example 
cyclohexylmethyl, 1- or 2-cyclohexylethyl, carboxylmethyl, 
2-carboxylethyl, 2- or 3-carboxylpropyl, trifluoromethyl, 2-chloroethyl, 
2-cyclohexyloxyethyl, phenoxymethyl, 2-phenoxyethyl, 2- or 
3-phenoxypropyl, benzyl, 2-methylbenzyl, 1- or 2-phenylethyl, 
2-hydroxyethyl, 2- or 3-hydroxypropyl, 2-cyanoethyl, 2- or 3-cyanopropyl, 
2-acetyloxyethyl, 2- or 3-acetyloxypropyl, 2-isobutyryloxyethyl, 2- or 
3-isobutyryloxypropyl, 2-methoxycarbonylethyl, 2- or 
3-methoxycarbonylpropyl, 2-ethoxycarbonylethyl, 2- or 
3-ethoxycarbonylpropyl, 2-methoxycarbonyloxyethyl, 2- or 
3-methoxycarbonyloxypropyl, 2-ethoxycarbonyloxyethyl, 2- or 
3-ethoxycarbonyloxypropyl, 2-butoxycarbonyloxyethyl, 2- or 
3-butoxycarbonyloxypropyl, 2-(2-phenylethoxycarbonyloxy)ethyl, 2- or 
3-(2-phenylethoxycarbonyloxy)propyl, 2-(2-ethoxyethoxycarbonyloxy)ethyl, 
2- or 3-(2-ethoxyethoxycarbonyloxy)propyl, 2-methylaminocarbonyloxyethyl 
or 2-ethylaminocarbonyloxyethyl. 
Q.sup.1, Q.sup.2, Q.sup.3, Z.sup.2 and Z.sup.6 may each also be for example 
fluorine, chlorine or bromine. 
Q.sup.1, Q.sup.2, Q.sup.3 and Z.sup.6 may each also be for example 
fluoromethyl, difluoromethyl, trifluoromethyl, 1,1,1-trifluoroethyl, 
pentylfluoroethyl, bis(trifluoromethyl)methyl, heptafluoropropyl, 
methylthio, ethylthio, propylthio, isopropylthio, butylthio, isobutylthio, 
sec-butylthio, pentylthio, isopentylthio, neopentylthio, tert-pentylthio 
or hexylthio. 
Q.sup.1, Q.sup.2 and Q.sup.3 may each also be for example phenoxy, 2-, 3- 
or 4-methylphenoxy, 2-, 3- or 4-methoxyphenoxy or 2-, 3- or 
4-chlorophenoxy. 
Z.sup.1 may also be for example methylsulfonylamino, ethylsulfonylamino, 
propylsulfonylamino, isopropylsulfonylamino, butylsulfonylamino, 
pentylsulfonylamino, hexylsulfonylamino, mono- or 
dimethylaminosulfonylamino, mono- or diethylaminosulfonylamino, mono- or 
dipropylaminosulfonylamino, mono- or diisopropylaminosulfonylamino, mono- 
or dibutylaminosulfonylamino, mono- or dipentylaminosulfonylamino, mono- 
or dihexylaminosulfonylamino or (N-methyl-N-ethylaminosulfonyl)amino. 
Z.sup.6 may also be for example benzyl, 2-methylbenzyl, 2,4-dimethylbenzyl, 
2-methoxybenzyl, 2,4-dimethoxybenzyl, methylamino, ethylamino, 
propylamino, isopropylamino, butylamino, pentylamino or hexylamino. 
Z.sup.3 and Z.sup.4 may each also be for example allyl or methallyl. 
Z.sup.3 and Z.sup.4 combined with the nitrogen atom joining them together 
into a 5- or 6-membered saturated heterocyclic radical with or without 
further hetero atoms can be for example pyrrolidinyl, piperidinyl, 
morpholinyl, piperazinyl or N--(C.sub.1 -C.sub.4 -alkyl)piperazinyl. 
Q.sup.1 and Q.sup.2 combined with the nitrogen atom joining them together 
into a 5- or 6-membered carbocyclic or heterocyclic ring can be for 
example a pyrrole, benzene or pyridine ring. These rings may also be 
substituted and/or saturated. R.sup.3 is derived from a 5- or 6-membered 
aromatic heterocyclic radical which may be benzofused and which has one or 
more hetero atoms selected from the group consisting of nitrogen, oxygen 
and sulfur. 
Suitable heterocyclic species, substituted or unsubstituted, from which 
R.sup.3 is derived include for example pyrrole, furan, thiophene, 
pyrazole, imidazole, oxazole, thiazole, isothiazole, 1,2,4-triazole, 
1,2,4-oxadiazole, 1,3,4-oxadiazole, 1,2,4-thiadiazole, 1,3,4-thiadiazole, 
pyridine, pyridazine, pyrimidine or pyrazine. 
Attention may be drawn in particular to heterocycles of the pyrrole, 
thiophene, isoxazole, pyridine or pyridazine series. 
Suitable R.sup.3 --Co or R.sup.3 --SO.sub.2 radicals include in particular 
those 5- or 6-membered aromatic heterocyclic radicals which are derived 
from the following heterocyclic carboxylic acids R.sup.3 --COOH or 
sulfonic acids R.sup.3 --SO.sub.3 H: 
##STR4## 
where L is C.sub.1 -C.sub.4 -alkyl in each case. 
Suitable R.sup.3 radicals include in particular the radicals of the 
formulae IIIa to IIIj in which the carboxyl or sulfonic acid radicals have 
been replaced by a single bond. 
Preference is given to methine dyes of the formula I where Q.sup.1, Q.sup.2 
and Q.sup.3 are independently of one another hydrogen, halogen, C.sub.1 
-C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy, formylamino or a radical of the 
formula --NH--CO--R.sup.1 or --NH--CO--OR.sup.1, where R.sup.1 is in each 
case as defined above. 
Preference is further given to methine dyes of the formula I where K is a 
radical of the formula IIa, Iic or IIi, especially the radical of the 
formula IIa. 
Preference is further given to methine dyes of the formula I where at least 
one of Q.sup.2 or Q.sup.3 is formylamino and Q.sup.1 is not formylamino. 
Particular preference is given to methine dyes of the formula I where 
Q.sup.1 is hydrogen, C.sub.1 -C.sub.4 -alkyl, halogen or a radical of the 
formula --NH--CO--R.sup.1 where R.sup.1 is C.sub.1 -C.sub.6 -alkyl which 
may be phenyl-, halogen- or hydroxyl-substituted or cyclohexyl, and 
Q.sup.2 and Q.sup.3 are independently of each other hydrogen, C.sub.1 
-C.sub.4 -alkyl, formylamino or a radical of the formula --NH--CO--R.sup.1 
where R.sup.1 is C.sub.1 -C.sub.6 -alkyl or tolyl. 
Very particular preference is given to methine dyes of the formula Ia 
##STR5## 
where X is nitrogen or a radical of the formula C--Q.sup.1, nitrogen being 
particularly preferred, 
Z.sup.1 is hydrogen, C.sub.1 -C.sub.4 -alkyl or C.sub.2 -C.sub.5 
-alkanoylamino, 
Z.sup.3 and Z.sup.4 are independently of each other C.sub.1 -C.sub.6 -alkyl 
which may be hydroxyl-substituted, benzyl, cyclohexyl, phenyl or tolyl, 
Q.sup.1 is hydrogen, C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy or a 
radical of the formula --NH--CO--R.sup.1, and 
Q.sup.2 and Q.sup.3 are independently of each other hydrogen, C.sub.1 
-C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy, formylamino or a radical of the 
formula --NH--CO--R.sup.1 or --NH--CO--OR.sup.1 where R.sup.1 is in each 
case C.sub.1 -C.sub.6 -alkyl which may be hydroxyl-substituted, benzyl, 
cyclohexyl, phenyl or tolyl, 
with the proviso that at least one of Q.sup.2 or Q.sup.3 is formylamino. 
Of particular interest are methine dyes of the formula Ia where 
Z.sup.1 is hydrogen, methyl, ethyl or C.sub.2 -C.sub.5 -alkanoylamino, 
Z.sup.3 and Z.sup.4 are independently of each other C.sub.1 -C.sub.6 -alkyl 
or benzyl, 
Q.sup.1 is hydrogen, C.sub.1 -C.sub.4 -alkyl or C.sub.2 -C.sub.5 
-alkanoylamino, and 
Q.sup.2 and Q.sup.3 are independently of each other hydrogen, C.sub.1 
-C.sub.4 -alkyl, C.sub.1 -C.sub.5 -alkanoylamino, benzoylamino or 
methylbenzoylamino. 
The methine dyes of the formula I can be obtained for example by the 
methods mentioned in U.S. Pat. No. 5,310,942. 
For example, a nitroso compound of the formula IV 
EQU K--N.dbd.O (IV), 
where K is as defined above, can be condensed with a hydroxyaromatic of the 
formula V 
##STR6## 
where Q.sup.1, Q.sup.2, Q.sup.3 and X are each as defined above. 
It is also possible to couple amines of the formula VI 
EQU K--NH.sub.2 (VI), 
where K is in each case as defined above, oxidatively with the 
hydroxyaromatics of the formula V. 
The present invention further provides a process for transferring dyes from 
a transfer to plastic-coated paper by diffusion or sublimation with the 
aid of an energy source, which comprises using a transfer on which there 
is or are one or more methine dyes of the formula I. 
To make the transfers required for the process of the present invention, 
the methine dyes of the formula I are incorporated in a suitable organic 
solvent or a mixture of solvents with one or more binders with or without 
auxiliaries to form a printing ink. This printing ink preferably contains 
the dyes in a molecularly disperse, ie. dissolved, form. The printing ink 
can be applied to the inert support by means of a doctor blade and air 
dried. Suitable organic solvents for the dyes include for example those in 
which the solubility of the dyes at a temperature of 20.degree. C. is 
greater than 1% by weight, preferably greater than 5% by weight. 
Examples are ethanol, propanol, isobutanol, tetrahydrofuran, methylene 
chloride, methyl ethyl ketone, cyclopentanone, cyclohexanone, toluene, 
chlorobenzene or mixtures thereof. 
Suitable binders include all resins or polymer materials which are soluble 
in organic solvents and which are capable of binding the dyes to the inert 
support sufficiently firmly as to prevent rubbing off. Preference is given 
to those binders which, after the air drying of the printing ink, include 
the dyes in the form of a clear, transparent film without any visible 
crystallization of the dyes. 
Such binders are mentioned for example in U.S. Pat. No. 5,132,438 or in the 
pertinent patent applications cited therein. Also suitable are saturated 
linear polyesters. 
Preferred binders include ethylcellulose, ethylhydroxyethylcellulose, 
polyvinyl butyral, polyvinyl acetate, cellulose propionate or saturated 
linear polyesters. 
The weight ratio of binder: dye generally ranges from 1:1 to 10:1. 
Suitable auxiliaries include for example release agents as mentioned in 
U.S. Pat. No. 5,132,438 or the pertinent patent applications cited 
therein. Also suitable are especially organic additives which prevent the 
crystallizing out of the transfer dyes in the course of storage or on 
heating of the color ribbon, for example cholesterol or vanillin. 
Suitable inert supports are described for example in U.S. Pat. No. 
5,132,438 or in the pertinent patent applications cited therein. The 
thickness of the support generally ranges from 3 to 30 .mu.m, preferably 
from 5 to 10 .mu.m. 
Suitable dye receiver layers include in principle all thermally stable 
plastics layers with affinity for the dyes to be transferred, for example 
modified polycarbonates or polyesters. Further details can be found for 
example in U.S. Pat. No. 5,132,438 or the pertinent patent applications 
cited therein. 
The process of transfer is effected by means of an energy source, for 
example by means of a laser or a thermal head, for which the latter has to 
be heatable to a temperature of .gtoreq.300.degree. C. so that the 
transfer of the dye can take place within the time range t: 0&lt;t &lt;15 msec. 
The dye migrates out of the transfer sheet and diffuses into the surface 
coating of the receiving medium. 
The methine dyes of the formula I used in the process of the present 
invention are notable for advantageous application properties. They 
exhibit high solubility in the color ribbon (good compatibility with the 
binder), a high stability in the printing ink, good transferability, high 
image stability (ie. good lightfastness and also good stability to 
environmental effects, for example moisture, temperature or chemicals), 
and permit flexible coloristic adaptation to given subtractive primary 
colors as part of an optimal trichromat. They are also notable for high 
brilliance owing to the high transparency in the blue and green parts of 
the spectrum. 
The dyes of the formula I according to the present invention are also 
advantageously useful for dyeing synthetic materials, for example 
polyesters, polyamides or polycarbonates. Particularly suitable are 
materials in textile form, such as fibers, yarns, threads, knits, wovens 
or nonwovens composed of polyester or polyamide or else polyester-cotton 
blend fabrics. The methine dyes of the formula I are also suitable for 
dyeing keratinous fibers, for example hairs or furs. 
The novel dyes of the formula I are also advantageously useful for 
manufacturing color filters as described for example in EP-A-399 473. 
Finally, they can also be used with advantage as colorants in 
electrophotographic toners. 
The Examples which follow illustrate the invention. 
A) Preparation 
Example 1 
5.35 g (0.025 mol) of 4-diethylamino-2-methylaniline hydrochloride and 3.45 
g (0.025 mol) of 2-formylamino-3-hydroxypyridine (prepared as described in 
J. Org. Chem., 36 (1971), 3238-40) were dissolved in 70 ml of methanol. To 
this solution were added 50 ml of water and 7.95 g (0.075 mol) of sodium 
carbonate dissolved in 50 ml of water. Then 6.8 g (0.03 mol) of ammonium 
peroxodisulfate dissolved in 50 ml of water were added dropwise at a 
temperature maintained within the range from 15.degree. C. to 20.degree. 
C. The batch was subsequently stirred for 30 min and filtered with 
suction, and the filter residue was washed with water and dried at room 
temperature to leave, in a 36% yield, the dye of the formula 
##STR7## 
The dye was recrystallized from isopropanol. 
mp.: 140.degree. C. 
.lambda..sub.max : 633 nm (tetrahydrofuran) 
.epsilon.: 
##EQU1## 
(chloroform) 
Example 2 
5.15 g (0.025 mol) of 4-diethylamino-2-acetylaminoaniline were dissolved in 
50 ml of water and 20 ml of concentrated hydrochloric acid. 10 ml of 23% 
strength by weight aqueous sodium nitrite solution were added dropwise at 
from 0.degree. to 50.degree..degree.C. and the mixture was subsequently 
stirred at from 0.degree. to 5.degree. C. for 2 h. The resulting nitroso 
compound was admixed with 100 ml of ethyl acetate and adjusted with 25% 
strength by weight aqueous ammonia solution to pH 8 at from 0.degree. to 
10.degree. C. The organic phase was separated off, concentrated and 
redissolved in methanol. This methanolic solution of the nitroso compound 
was admixed with Raney nickel and reduced with hydrogen. On completion of 
the reduction the catalyst was filtered off and the solution was 
concentrated. The concentrate was added to 3.45 g (0.025 mol) of 
2-formylamino-3-hydroxypyridine and both components were dissolved with 70 
ml of methanol. This was followed by dilution with 50 ml of water, the 
addition of 5.3 g (0.05 mol) of sodium carbonate dissolved in 50 ml of 
water and dropwise addition at from 10.degree. to 20.degree. C. of 6.8 g 
(0.03 mol) of ammonium peroxodisulfate dissolved in 50 ml of water. The 
mixture was subsequently stirred for 30 min and filtered with suction, and 
the filter residue was washed with 1:1 v/v methanol/water and then with 
water and dried to leave, in a 47% yield, the dye of the formula 
##STR8## 
mp.: 189.degree. C. max: 644 nm (tetrahydrofuran) 
Example 3 
8.2 g (0.025 mol) of 4-dibutylamino-2-acetylaminoaniline (79.4% strength by 
weight) were nitrosated and reduced as described in Example 2. 3.45 g 
(0.025 mol) of 2-formylamino-3-hydroxypyridine were dissolved in 70 ml of 
methanol together with the above-reduced compound. 5.3 g (0.05 mol) of 
sodium carbonate in solid form were sprinkled in, and then 6.8 g (0.03 
mol) of ammonium peroxodisulfate dissolved in 50 ml of water were slowly 
added dropwise at about 10.degree. C. The batch was subsequently stirred 
for 30 min and filtered with suction, and the filter residue was washed 
with water and dried at room temperature to leave, in a 15% yield, the dye 
of the formula 
##STR9## 
mp.: 155.degree. C. .lambda..sub.max : 648 nm (tetrahydrofuran) 
.epsilon.: 1/mol.multidot.cm (chloroform) 
The same method was used to obtain the dyes of Tables 1 and 2 below. In 
addition to the absorption maximum (measured in tetrahydrofuran) the 
tables also contain the R.sub.f value on silica gel and the volume ratio 
of the toluene (T)/ethyl acetate (E) used as mobile phase in the 
chromatography. 
TABLE 1 
______________________________________ 
##STR10## 
Ex. .lambda..sub.max 
R.sub.f 
No. K nm! value 
T/E 
______________________________________ 
##STR11## 638 0.49 3:2 
5 
##STR12## 636 0.43 3:2 
6 
##STR13## 640 0.31 0:1 
7 
##STR14## 652 0.43 3:2 
8 
##STR15## 646 0.27 3:2 
9 
##STR16## 637 0.50 3:2 
10 
##STR17## 645 0.22 3:2 
11 
##STR18## 607 0.50 0:1 
12 
##STR19## 628 0.26 3:2 
13 
##STR20## 626 0.28 3:2 
14 
##STR21## 640 0.17 3:2 
15 
##STR22## 653 0.43 3:2 
16 
##STR23## 629 
17 
##STR24## 0.39 3:2 
18 
##STR25## 622 0.45 3:2 
19 
##STR26## 609 0.23 3:2 
20 
##STR27## 620 0.40 3:2 
21 
##STR28## 620 0.35 3:2 
22 
##STR29## 622 0.35 3:2 
23 
##STR30## 634 0.25 3:2 
24 
##STR31## 650 0.35 3:2 
25 
##STR32## 631 0.32 3:2 
______________________________________ 
TABLE 2 
______________________________________ 
##STR33## 
Ex. .lambda..sub.max 
R.sub.f 
No. K nm! value 
T/E 
______________________________________ 
26 
##STR34## 628 0.20 3:2 
27 
##STR35## 614 0.33 3:2 
28 
##STR36## 640 0.40 3:2 
29 
##STR37## 631 0.27 3:2 
30 
##STR38## 626 0.31 3:2 
31 
##STR39## 598 0.26 3:2 
32 
##STR40## 614 0.37 3:2 
33 
##STR41## 626 0.29 3:2 
34 
##STR42## 607 0.46 3:2 
35 
##STR43## 627 0.46 3:2 
36 
##STR44## 642 0.52 0:1 
______________________________________ 
The below-mentioned dyes likewise have advantageous properties. 
__________________________________________________________________________ 
Ex. 
No. Hue 
__________________________________________________________________________ 
37 
##STR45## cyan 
38 
##STR46## cyan 
39 
##STR47## cyan 
40 
##STR48## blue 
41 
##STR49## cyan 
42 
##STR50## cyan 
43 
##STR51## turquoise 
44 
##STR52## turquoise 
45 
##STR53## cyan 
46 
##STR54## cyan 
47 
##STR55## cyan 
48 
##STR56## blue 
49 
##STR57## cyan 
50 
##STR58## cyan 
51 
##STR59## cyan 
52 
##STR60## cyan 
53 
##STR61## blue 
__________________________________________________________________________ 
B) Application in Thermal Transfer 
General method: 
a) 10 g of dye are stirred, if necessary with brief heating to 
80.degree.-90.degree. C., into 100 g of a 10% strength by weight solution 
of a binder in 4.5:2:2 v/v/v methyl ethyl ketone/toluene/cyclohexanone. 
The mixture is applied with a 6 .mu.m doctor blade to a 6 .mu.m thick 
polyester film which has a suitable subbing layer on the back and is blown 
dry with a hair dryer in the course of 1 minute. Before the color ribbon 
can be printed, it has to be air dried for at least a further 24 hours, 
since residual solvents can impair the printing process. 
b) The color ribbons are printed on an experimental computer-controlled 
apparatus equipped with a commercial thermal printing head onto commercial 
videoprint paper. 
The voltage is altered to control the energy emitted by the thermal 
printing head, the length of a pulse having been set to 7 ms and only one 
pulse being emitted at a time. The emitted energy level ranges from 0.5 to 
2.0 mJ/dot. 
Since the depth of the color is directly proportional to the supplied 
energy, it is possible to produce a color wedge for spectroscopic 
evaluation. 
The depth of the color is plotted against the supplied energy per heating 
element to determine the Q* value (=energy in mJ for the absorbance value 
of 1) and the gradient m in 1/mJ. 
The results obtained are listed in the Table below. Unless other-wise 
stated, the binder used was based on saturated linear polyester and the 
receiving medium used was color videoprint paper from Hitachi. 
TABLE 3 
______________________________________ 
Dye No. Q* mJ/dot! 
m l/mJ! 
______________________________________ 
1 0.74 4.4 
0.75.sup.a) 
4.4.sup.a) 
1.08.sup.b) 
3.9.sup.b) 
2 0.93 2.9 
0.85.sup.a) 
2.9.sup.a) 
1.29.sup.b) 
2.3.sup.b) 
4 0.77 4.1 
5 0.76 3.9 
6 0.90 2.9 
7 0.92 3.0 
10 0.90 3.2 
19 1.02 4.0 
______________________________________ 
.sup.a) Binder: polyvinyl butyral 
.sup.b) Binder: cellulose propionate 
Receiving medium: color videoprint paper (SV 100) from Kodak