Note: Descriptions are shown in the official language in which they were submitted.
O.Z. 005~/422~5
Bichromophoric methine dye~
The present invention relates to novel bichromo-
phoriG methine dyes of the formula I
A=N~Z--L--Y~=B
where
A and B are identical or different and each is indepen-
dently of the other the radical of an acidic CH
compound,
W is nitrogen or the radical
CN
-C H=
L is a bridge member which does not permit any con- -
jugation of ~-electrons between the radicals Z and
Y, and
Z and Y are identical or different and in conjunction
with the bridge member L are each independently of
the other a radical of the formula
~N--L-- , ~ R 2 CH 3
(~Ia) (IIb) (IIc)
_, ~N--Rl, ~
~IId) (IIe) (IIf)
Il
~N - L - or R4 ~ ~ Rl
(IIg) (IIh)
where
-- 2 0 ~
2 O.Z. 0050/42225
n is 0 or 1,
R1 and R5 are identical or different and each is indepen-
dently of the other alkyl, alkoxyalkyl, alkoxy-
carbonylalkyl or alkanoyloxyalkyl, which may ~ach
have up to 10 carbon atoms and be hydroxyl- or
cyano-sub~titutad, hydrogen, benzyl, cyclohexyl,
phenyl or tolyl,
R2 i5 hydrogen, C1-C8-alkyl, C1-C6-alkoxy or a radical of
the formula R7-Co-NH-, R7-o-Co-NX- or R7-So2NH-, where
R7 is phenyl, tolyl, benzyl or C1-C8-alkyl which may
be interrupted by one or two o~ygen atom~ in ether
function,
R3 is hydrogen, methyl, ethyl or Cl-C4-alkoxy,
R4 is hydrogen, halogen, C1-Ca-alkyl, un~ub~tituted or
Cl-Cq-alkyl- or Cl-C4-alkoxy-~ub~tituted phenyl,
un~ubstituted or Cl-C4-alkyl- or Cl-C4-alkoxy-sub-
stituted benzyl, cyclohexyl, thienyl or the radical
-NHR1, where Rl is a~ defined above, and
R~ is hydrogen or Cl-C8-alkyl, and to a proce~ for the
thermal tran~fer of these dyes.
Bichromophoric methine dyes with dicyanovinyl
radicals are known for example from GB-~-1,201,925,
US-A~3,553,245, DE-A-1,569,67B, D~ A-2,519,59~ or
DE-A-3,020,473.
It iB an object of the present invention to
provide novel bichromophoric methine dyes which should
posse~s advantageou~ application properties.
We have found that ~hi~ ob-Ject i~ achieved by the
bichromophoric methine dyes of the formula I defined at
the beginning.
Any alkyl or alkylene appearins in the above-
mentioned formula I may be either straight-chain o.r
branched.
The bridge member L which does not permit any
con~ugation of ~-electrons between the radicals Z and Y
conforms in general to the formula
-EI-O-E2-
~ ~ 2 a ~
3 O.Z 0~50~42225
where
D is a chemical bond, oxygen, -SO2-, -O-CO-O-,
1,4-cyclohexylene, phenylene, -O-CO-(CH2)l-CO-O,
-O- ( CH2 ) m~~ t
-o-C0 ~ o-(cH2)m-o ~ C0-0- where 1 is 1-10 and
cO-O-
m i5 2-10, -0-C0 ~ cO-0- -0-cO
-0-C0 ~ or 0-C0 ~ o_ and
CO--O--
and E2 are identical or different and each i8 indepen-
dently of the other a ~hemical bond or Cl-Cl5-alky-
lene.
Suitable acidic CH compoundfi AH2 or BH2 from which
the radicals A and B in formula I are derived are for
example nitromethane, nitroethane and a compound of the
formula
C / /CoX
Xl X3 1 4
(IVa) (IVb) (I~c)
o o
X S~N~N--X 5 X 5`NJ~N--X S
0~0 ' ~CH 2 orN CH 2--CON~ 2
(IVd) (IVe) (IVf)
where
X1 is cyano, nitro, C1-C4-alkanoyl, unsubstituted or
Cl-C4-alkyl-, C1-C~-alkoxy- or halogen-3ubstituted
benzoyl, Cl-C4-alkylsulfon~l, unsubstituted or Cl-C4-
alkyl-, Cl-C4~alkoxy or halogen-substituted phenyl-
-sulfonyl, carboxyl, Cl-C~-alko~ycarbonyl which may be
4 O.Z. 0050/422~
- interrupted by 1 or 2 oxygen atom~ in e~her func-
tion, C5-C7-cycloalkoxycarbonyl, phenoxycarbonyl,
caxbamoyl, Cl-C6-mono- or -dialkylcarbamoyl which
may be interrupted by 1 or 2 oxygen atoms in ether
function, C5-C7-mono- or -dicycloalkylcarbamoyl,
unsubstituted or C1-C4-alkyl-, Cl-C4-alkoxy- or
halogen-substituted phenylcarbamoyl, unsubstituted
or Cl-C4-alkyl-, cyano-, C1-C4-alkoxy-, halogen- or
nitro-substituted phenyl, 2-benzothiazolyl, 2-benz-
imidazolyl, 5-phenyl-1,3,4-thiadiazol-2-yl or
2-hydroxyquinoxalin-3-yl,
X2 is Cl~C~-alkyl or Cl-C4-alkoxy,
X3 iS Cl-C4-alkoxycarbonyl~ phenylcarbamoyl or 2-benz-
Lmidazolyl,
X4 iS Cl-C4-alkyl, and
X5 iS hydrogen, Cl-C4-alkyl or phenyl.
Radicals which may he mentioned in particular
here are those derived from acidic CH compounds of the
formula IVa or IVb.
Suitable radical~ Rl, R2, R4, R5, R~ and R7 are for
example methyl, ethyl, propyl, isopropyl, butyl, iso-
butyl, sec-butyl, tert-butyl, pentyl, isopentyl, neo-
pentyl, tert-pentyl, hexyl, 2-methylpentyl, heptyl,
octyl, 2-ethylhexyl and i~ooctyl.
R2 may also be for example, like R3, methoxy,
ethoxy, propoxy, butox~ or 3ec-butoxy.
Rl and R5 may each also be for example nonyl,
i ononyl, decyl, isodecyl, 2-metho~yethyl, 2-ethoxyethyl,
2-propoxyethyl, 2-butoxyethyl, 2- or 3-methoxypropyl, 2-
or 3-ethoxypropyl, 2- or 3-propoxypropyl, 2- or 3-butoxy-
propyl, 4-methoxybutyl, 4-ethoxybutyl, 4-butoxybutyl,
2-cy~noethyl, 3-cyanopropyl, 4-cyanobutyl, 2-hydroxy-
e~hyl,
O.z. 00~0/4222
-CH2) 2--O C--CH3, --(CH2) 2--C--0--C4Hg, --(CH2)4--C--O--CH(CH3) 2
or
R
--(CH2) 3--C--O--C4Hg -
R4 may also be for example phenyl, 2-, 3- or
4-methylphenyl, 2- or 4-isopropylphenyl, 2-butylphenyl,
2-, 3- or 4-methoxyphenyl, 2-propoxyphenyl, 4-butoxy-
S phenyl, 2-(but-2-oxy)phenyl, benzyl, 2-, 3 or 4-methyl-
benzyl, 2-, 3- or 4-methoxybenzyl, fluorin~, chlorine,
bromine, 2-thi~nyl or 3-thienyl.
R2 may also be for example pentyloxy, isopentyl-
oxy, neopentyloxy, hexyloxy, acetylamino, propionylamino,
butyrylamino, 3-oxabutylcarbonylamino, 3-oxapentyl-
carbonylamino,3-oxaheptylcarbonylamino,3,6-dioxaheptyl-
carbonylamino, 3,6-dioxaoctylcarbonylamino, benzyl-
carbonylamino, 2-, 3- or 4-tolylcarbonylamino, methoxy-
carbonylamino,ethoxycarbonylamino,propoxycarbonylamino,
isopropoxycarbonylamino, butoxycarbonylamino, pentyloxy-
carbonylamino, hexyloxycarbonylamino, 3-oxapentyloxy-
carbonylamino, b~nzylo~ycarbonylamino, methylsulfonyl-
amino, ethylsulfonylamino, propylsulfonylamino, iso-
propyl~ulfonylamino or butylsulfonylamino.
X1 is for example methoxycarbonyl, ethoxy~car-
bonyl, propoxycarbonyl, isopropoxycarbonyl, butoxy-
carbonyl, 2-methoxysthoxycarbonyl, methylcarbamoyl,
ethylcarbamoyl, 2-methoxyethylcarbamoyl, cyclopentyl-
oxycarbonyl, cyclohexyloxycarbonyl, cyclohep~yloxy-
carbonyl, cyclopentylcarbamoyl, cyclohexylcarhamoyl or
cycloheptylcarbamoyl.
E1 and E2 are each for example methylene,
1,2-et~ylQne, ethylidene, 1,2- or 1,3-propylene or l,4-,
1,3- or 2,3-bukylene.
7~ ~J
~ o,z, 0050/422Z5
D is for example
o o o o o o o .
Il 11 11 11 11 11 11 11
~C-CH 2--C~, ~C--( CH 2 ) 2--C~ ~C--( CH 2 ) 3--C--O--~ --O--C--( CH 2 ) 4-C~--,
O O O O O O
~C--( CH 2 ) 5--C~, --(}C--( CH 2 ) 6--C (}, --(}C--( CH 2 ) 7--C{~,
O O O O O O
~}C--( C H 2 ) 8 e{}, {)--C--( CH 2 ) g--C{)--, --(}C--( CH 2 ) I o--C-O--,
{)--(CH2)2~, {~(CH2)3--/}~ ~(CH2)4~, ~(CH2)5~, -O--(CH2)6-0--,
-{}(cH2)7 (}~ ~(CH2)8~, ~(CH2)9-0--, {}(cH2)lo--0--~
O O O O
~C~(CH2) 2~3C~, ~C~(CH2) 3~3C--O--,
O O O O
-o-C ~ o-(cH2)4 ~ C-O-, O e~ (CH2)5 ~ C-o-, -
o o o o
-o-c ~ (cH2, 6~e 0 O-e~ (CH2)7 ~ c-o-,
1l (CH2)s ~ c-o-, -o-C ~ (CH2)3 ~ c-o-
or -o-C ~ (CH2)lo ~ C-O-.
Preference is given to bichromophoric methine
dyes of the formula III
NC CN
C=N-Z- L-Y-N=C (III)
Q Q
where the radicals
Q are identical or di~ferent and each 18 cyano, C~-C6-
- alkoxycarbonyl or C1-C3-monoal~ylcarbamoyl, where the
alkyl group~ may in each ca3e be interrupted by l or
2 oxygen atom~ in ether function~ C5-C7-cycloalkoxy-
carbonyl, C5-C7-monocyclo lkylcarbamoyl, phenoxy-
carbonyl or monophsnylcarbamoyl, and
Z, L-and Y are aach a~ dsfined above.
J~
7 O.Z. 0050/422~5
Preference is further given to bichromophoric
methine dyes of the formula I where the radicals Z-L and
Y-L conform to the formulae IIa to IIg~
Preference is further given to bichromophoric
methine dyes of the formula I where
Rl and R5 are each independently of the other hydrogen,
unsubstituted or cyano- or acetoxy-~ubstituted Cl-C6-
alkyl, benzyl or cyclohexyl,
R2 is hydrogen, methyl, methoxy or acetylamino,
R3 is hydrogen, methyl, ethyl or methoxy,
R4 is hydrogen, Cl-C6-alkyl, unsubstituted or methyl-
or methoxy-substituted phenyl, 2-thienyl or
3-thienyl, and
R6 i8 hydrogen or Cl-C6-alkyl.
Particular preference is given to bichromophoric
methine dyes of the formula III where Q is cyano.
Particular preference is further given to
bichromophoric methine dyes of the formula I where the
bridge member L has the formula
-El-D-E2-
where
El and EZ are each indspendently of the other Cl-C4~alky-
lene and
D i a chemical bond, oxygen, -SO2-,
-O-CO-(C~2~l-C--~
-O-C ~ (C~2)m ~ C~ where 1 is from 2 to
cO~
4 and m i~ from6 to 10, -O-C ~ C~ o-C
or -C-C
CO~
~he novel methine dyes of formula I can be
obtained by method~ known per se, a~ described for
example in GB 1,201,925, US-A-3,553,245, D~-A-1,569,678,
DE-A-2,519,592, DR-A-3,020,473l US-A-2,889,335 or
EP-A-284,560.
- A pre~erred procedure compri~es for example first
2 ~
8 O.Z. 0050/42225
using an appropriate bridge member to link together the
two groups Z and Y which will act in the dye as donors
and then converting the resulting intermediates (herein-
after referred to as dye precursors) into bichromophoric
methine dyes I by the incorporation of for example
cyanovinyl groups.
The procedure will be exemplified in explanation
with synthesis schemes for preparing certain bichromo-
phoric methine dyes I. ~ere z, y~ Q, p~l, R2, R3, 1 and m
are each as defined above.
9 0OZ. 0050/~222
a) Synthesis of dye precur~or5
divinyl ~fone
ZH2 . ~ HZ--( CH 2 ) 2--50 2--CH=CH 2
¦ YH2
HZ--(CH2) 2--S2--(cH2) 2--YH
p,toluene~fonyl
chloride
HZ-(CH2)2-OH HZ--(CH2) 2~52~CH 3
~ ¦ HY--(CH2) 2--OH
HZ--(CH2) 2--YH HZ--(CH2) 2--(cH2) 2--'~H
b) Incorporation of ~ymmetrical acceptor groups into
the chromophores:
bl) Condensation
Sodium nitrite
H-Z-(C~)2-Y-H ----__________ ON_Z_ ( CH 2 ) 2 - Y - NO
hydrochloric acid
Condensation ¦ ~
CN~ ~CN
~C=N--Z--( CH 2 ) 2--Y-N=C~
~: Q Q
b2) Oxidative coupl'ng ~ CN
Silver nitrate C\2
: x
Ni~ration
~ ~ z (CH2)2 Y H - ~ H2N-Z-(CH2)2-Y-NH2
: R~ion
,.. . ... .
a
O.Z. 0050/42225
c) Incorporation of asymmetrical acceptor groups
CN R2
R3 R~
NC~ ~ RI R~ (CH2)m--C~CI
R3 (CH2) 1--OH
C N R 2 Ni~rosation
NC~ R I
C N ~N R 1 R 3
R3 (CH2)l{~c~(cH2)m-N~l
CN R 2 CN
NC~ Rl CH 2--X
C N "~--`N R 1 R 3 Condensation
R3 (CH2) I--O--C(}(CH2)m--N~
~NO
R2
CN R2
NC~ R 1
CN ~N~ 11 R 3
R3 (CH2) 1--0--CO~(CH2)m~~~N=C\CN
R2 X
The other dye precursor can be converted in a
similar manner9
The novel dye~ I ~how advantageou~ ~olubility in
organic 3slvent3.
The pre~ent invention further provides a novel
process for the thermal tran3fer of dye~.
In thermal transfex printing, a tran~fer sheet
which contains a thermally trans~erable dye within one or
moxe binders with or without suitable ~ssistants on a
support, is heated from the back with an energy source,
for example a thexmal head, in short thermal pulse
(duration: fractions of a ~econd), which cau~e~ the dye
to migrate out of the transfe.r sheet and to diffuse into
the surface coating of a receiving medium. The es~ential
~ f) ~
11 O.Z. 0050/42225
advantage of this process is that the amount of dye to be
transferred (and hence the color gradation3 can easily be
controlled via the energy to be emitted by the ener~y
source.
5In general, color recording i5 carried out using
the three subtractive primariec yellow, magenta and cyan
(and if necessary black). To permit optimum color
recording, the dyes must have the following properties:
- ready thermal transferability,
- minimal tendency to migrate within or out of the
surface coating of the receiving medium at room
temperature,
- high thermal and photochemical stability and resis-
tance to moisture and chemic~ls,
- suitable hue~ for subtractive color mixing,
- a high molar absorption coefficient,
- and no tendency to-cry~tallize out on storage of the
transfer sheet.
It i~ known from experience that these require-
20ments are very difficult to meet at one and the same
time.
For this reason, most of the dyec used for
thermal transfer printing do not have the required
property profile.
25It has now been found that the transfer of
bichromophoric methine dye~ from a support to plastic-
coated paper with the aid of a thermal head is advan-
tag20u81y pOBsible using a support on which there is or
are situated one or more dyes of the abovementioned
30formula I.
Compared with the dye~ hitherto used in existing
proce~3e~, the dyes tran~ferred in the process of the
in~ention generally are notable for improved fixation in
:~ the receiving medium at room temperature, readier thermal
35tran~ferability, higher light fastne~, higher ~tability
to moisture and chemical substances, better ~olubility in
organic solvents, higher color ribbon stability and
2 ~
12 O.Z. 0~50/42225
high~r cleanness of hue.
It i5 al30 surprising that the dyes of the
formula I are readily transferable and possess a high
color ribbon stability, despite having a very high
molecular weight.
Prior art thermal transfer printing systems
generally utilize mixtures of monochromophoric dyes in
order to absorb about a third of the incident white light
each in the cyan and in particular in the magenta region.
This requires that the dyes used must have exactly the
same transfer characteristicq in order that a given
output of the energy source used may produce equal
coloring~ in the receiving medium (receptor~. This
requirement is met in the process of the invention. One
result i~ that for example an improved black is obtained
on utilizing trichromatic systems.
Owing to their high molar extinction coefficients
and ~teep absorption flanks (high brilliance), the dyes
of the formula I used in the novel proces are advan-
tageously suitable for preparing a trichromatic systemrequired for subtractive color mixing.
In addition, the ready transferability permits a
wide range of receptor plastics and hence optimal adapta-
tion of the dyes within the overall syste~ (donor/recep-
tor).
To prepare the dye supports required for theprocess of the invention, the dye~ are incorporated into
a 3uitable organic solvent or into mixtures of solvents
with o~ or more binders and with or without assistants
to form a printing ink in which ths dye is preferably
present in a molecularly dispersed, ie. dissolved, form.
The printing ink can be applied to the inert support by
means of a dockor and air dried.
Suitable organic ~olvents for the dyes I are for
example those in which the solubility of the dye~ I at
20C i~ greater than 1% by weight, preferably qreater
than~5% by w~ight.
2~ ,3~
13 O.Z. 0~50/42225
Examples are ethanol, propanol, isobutanol,
tetrahydrofuran, methylene chloride, methyl ethyl ketone,
cyclopentanone, cyclohexanone, toluene, chlorobenzene and
mixtures thereof.
Suitable binders are all resins or polymer
materials which are soluble in organic solvents and which
are capable of binding the dye to the inert support in
such a way that it won't rub off. Preference is here
given to those binders whlch, after the printing ink has
been air dried, hold the dye in the form of a clear,
transparent film in which no visible crystallization of
the dye occurs.
Such binders are mentioned for example in earlier
Patent Application ~P-A-441,282 or in the relevant patent
applications cited therein. Furthermore, ~aturated linDar
polye ters may be mentioned.
Preferred binders are ethylcellulose, ethyl-
hydroxyethylcellulose, polyvinyl butyrate, polyvinyl
acetate and saturated linear polyesters.
The weight ratio of binder:dye ranges in general
from 1:1 to 10:1.
Suitable ~istant~ are for example release
agent~ a3 mentioned in earlier German Patent Application
P 40 04 612.5 or in the relevant patent application~
cited therein.
Suitable inert supports are described Por example
in the earlier Patent Application ~P-A^441,282 or in the
relevant patent application~ cit~d th~rein. The thickness
o~ tha support for the dye is in general from 3 to 30 ~m,
pr0ferably from 5 to 10 ~m.
The dye receptor layer can in principle be made
of any high temperature re~istant plastic having affinity
for the dyes to be tran ferred, for example modified
polycarbonate~ or polye ter3. Further details are di cer-
nible for example ~rom earlier Patent Application
EP-A-4~1,282 or the relevant Patent Application~ cited
therein.
~ ~3 ~ f
14 o.z. 0050/42225
Transfer is effected by means of an energy
source, for example by means of a laser or by means of a
thermal head which latter must be heatable to ~ 300C in
order that dye transfer may take place within the time
span t: 0 < t ~ 15 msec. In the course of transfer the
dye migrates out of the transfer sheet and diffuses into
the surface coating of the receiving medium.
The dyes of the present invention are also
advantageously suitable for dyeing synthetic materials,
for example polyesters, polyamides or polycarbonates.
Textile fabrics of polyester or polyamide or
polyester/cotton blends may be mentioned in par icular.
The novel dyes are al~o advantageous for th~
production of color filters, as described, for example,
in EP-A-399,473. Finally, they can also advantageously be
used as colorants for the production of toners for
electrophotography.
The Examples which follow will further illustrate
the invention. Percentages are by weight, unless other-
wise stated.I. Preparation of methine dye~
EXAMPLE A
CH~ CH2-CH2-O-II ~ (CH2)s ~ C-O-CH2-CH2 ~ H
50 g of 1,9-dibromononane, 58.1 g of ethyl
4-hydroxybenzoate and 94.2 g of potassium carbonate were
suspended at room temperature in 500 ml of N,N-dimethyl-
formamld2 (anhydrous) and then heated at 100C until
starting material was no longer detectable by thin layer
chromatography. The cold reaction mixkure was iltered
with suction, and the solvent was removed under reduced
pre~sure. The residue was recrystallized from methanol
(37.4 g of pure substance), admixed with 300 ml of
ethanol, and added to a mixture of 19.9 g of potassium
hydroxide in 260 ml of ethanol, and the mixture was
raised to the refluxing temperature. After complete
~ ',3
0.Z. 0050/42225
hydrolysis (check by TLC), the mixture was cooled down to
room temp~rature and filtered with suction, and the
residue was suspended in water, acidified by hydrochloric
acid, again filtered off with suction and washed neutral.
28.3 g of pure substance were o~tained.
lH NMR (CDCl3, TMS): ~ = 1.10 - 1.90 (m, 14 H,
CH2), 4.05 (t, 4 H), OCH2), 7.00 (d, 4 H, aromatic H),
7.90 (d, 4 H, aromatic H, 12.15 (s, 2 H, COOH) ppm
28 g of the product obtained were suspended in
120 ml of thionyl chloride and dissolved by heating to
the refluxing temperature. After the reaction had ended,
the solution was cooled down to room temperature, the
reaction prcduct wa~ precipitated with petroleum ether,
and the precipitate was filtered off with suction, washed
with petroleum ether (IR: COCl, 1760 - 1740 cm~l) and then
dissolved in 50 ml of methylene chloride. This solution
wa~ added dropwise to 22.9 g of N-(2-hydroxyethyl)-N-
ethyl-~-methylaniline, a spatula tip of 4-dimethylamino-
pyridine and 6.5 g o~ triethylamine in 50 ml of anhydrous
methylene chloride at from 0 to 5C. Then stirring wa~
continued at room temperature until ths reaction had
ended. ~he reaction mixture wa~ stirred into ice-water,
and the mixture was acidified with dilute hydrochloric
acid and extracted with methylene chloride. The organic
phase wa3 washed neutral with water and dried, and the
solvent was r~moved under reduced pre~ure lyield: 42 g,
R~ value: 0.32 ~:1 v/v toluene/ethyl acetate - TLC alumi-
num sheet~, silica gel 60 F254 from E. Merck).
EXAMPLE B
NC~c N ~ ,C2H5 H5C2~ ~ N-C~
10.16 g of the compound of the formula
CH3 N`C ,N ~ H3
were dis~olvedin 100 ml of water and 50 ml of concentrated
-
16 0.Z. 0050/42225
hydrochloric acid. 19 ml of 23% strength by weight
aqueous sodium nitrite solution were then added dropwise
at 0-5C, and the mixture was subsequently stirred at
0-5C for 2 hours. After the nitrosation had ended, the
mixture was adjusted to pH 8 with 25% strength by weight
aqueous ammonium hydroxide solution, and the nitroso
compound was taken up in neutral form in methylene
chloride. After 4 g of malodinitrile and 30 ml of acetic
anhydride had been added, the mixture was briefly heated
to 70C and then cooled down to room tempçrature. On
addition of 100 ml of isopropanol and 10 ml of water the
target product precipitated and was filtered off with
suction. Washing with methanol left 5.3 g of dye (^ 35.8%
of theory); melting point: 86C; R~ value 0.33 9:1 v/v
toluene/ethyl acetate ~LC aluminum sheets, silica gel
60 F254 from E. Merck; ~ (tetrahydrofuran)o 497 nm.
EXAMPLE C
NC ~3 C 2H4~CO--CH 2--CH 2--CO--O--C 2H 4' ~N C~CN
11.12 g of the compound of formula
~N~ C 2H5~N_~
CH 3 C 2H4~CO--CH 2--CH 2--CO~C 2H4 CH 3
were nitrosated as described in Example B and then
sondensed with 3.4 g of malodinitrile in 30 ml of acetic
anhydride. The reaction mixture W?S subsequently admixed
with 220 ml o~ i~opropanol, whereupon an oil precipitated
which on ~tanding over the weekend formed crystals. The
precipitate was filtered off with ~uction and washed with
a little isopropanol. 6.04 g (- 40.4% of theory) of dye
were obtained. R~ value: 0.20 8:2 v/v toluene/ethyl
acetate TLC aluminum sheets, silica gel 60 F254 from E.
Merck; ~maX (tetrahydrofuran): 492 nm.
The same method wa~ u~ed to obtain the dyes of
formula
.
-
17 O.Z. 0050/4~225
,C=N~N~ ,N~rJ=C
li~ted below in Table 1.
TABLE 1
Example No. E L R~ value ~m~ [
D H ~CO~CO--O 0, 46 a) 484
E H O--CO~CO O0, 46 a) ~85
f CH3 ~C~3co O 0, 30 b) 492
a) Eluent: 3:2 v/v toluene/ethyl acetate
5 b) Eluent: 8:2 ~/v toluene/ethyl acetate
In each case development was carried out on TLC aluminum
sheets, ~ilica gel 60 F254 from E. Merck.
II. Transfer of methine dye~
For a ~imple qùantitative examination of the
tran~fer characteristics of the dyes, large hotplates
were used instead of a thermal printing head and the
tran~fer temperature was varied within the range
70C < T ~ 120C, the transfer time having besn fixed at
2 minutes.
~) General recipe for coating the ~upport with dye:
1 g of binder wa3 dis~olved in 8 ml of 8:2 v/v
toluene/ethanol at 40-50C. A solution of x g of dye in
5 ml of tetrahydrofuran wa~ added with stirring and any
in~oluble residue wa filtered off. The print paste thu~
obtained wa~ applied with an 80 ~m doctvr to a polyester
aheet tthickne~s: 6-10 ~m) and dried with a hairdryer.
~) Te~t for thermal tran~ferability
The dye~ used were te~ted in the following way:
the polyester ~heet donor containing the in-test dye in
the coating composition on the fxont wa~ placed with the
coated front on a commercially available ~heet of
2, ~ t 3-j
18 O.Z. OOS0/42225
receptor paper (hereinafter described) and pressed down.
Donor and receptor were then ~Jrapped in aluminum foil and
heated between two hotplates at variou temperatures T
(within the temperature range 70~C < T < 120C). The
amount of dye which diffuses into the bright plaitics
layer of the receptor is proportional to the optical
density (= absorbance A). The latter was determined
photometrically. A plot of the logarithm of the absor-
bance A of the colored receptor papers measured within
the temperature range between 40 and 110C against the
reciprocal of the corresponding absolute temperature is
a straight line from whose slope it is possible to
calculate the activation energy ~ET for the transfer
experiment:
~log~
~ET = 2 . 3 X R X ---
To complete the characterization, the temperature
T* [C], at which the absor~ance A of the colored recep-
tor papers attains the value 1, is additionally takenfrom the plots.
The dyes li~ted below in Table 2 were processed
according to ~) and the resulting dye-coated supports
were examined for transferability according to ~). The
Table lists for each example the thermal transfer para-
meters T* and ~ET~ the absorption maxima of the dyes ~m~
(measured in methylene chloride), the binder~ used and
the weight ratio of the dye: binder.
The key to the abbreviation~ is as follows:
D Y dye
B = binder
V = Vylon~ 290 from Toyobo
CP = cellulose propionate
HCVPP - Hitachi Color Video Print Paper ~receptor)
PBTP = polybutylene terephthalate film (receptor)
19 0, Z . 0050/42225
,n u~
<
* V V
~ cr ~
Z Z ~- .
~, a
I I ~ ~
m , ~
~ = O ~. i CL T 1 T
o o ~
Z O O
a)
~ ~ g ~
O.Z~ 0050/42225
The same method can be used to transfer the
following methine dyes:
Example No.
7 NC~( ~`CH 3 CH SO CH 2--CH 2' ~3CN)~CN
H 3C
~N~H 3 CH 2--50 2--CH 2--CH 2 ~CN
NC~(C~CH 2--CH 2--50 2--CH 2--CH 2 ~CN
CH3 CH3
NC-4 ~ CH 2--CH 2--S0 2--CH rCH 2 ~CN
CH3
I l NC~ ~3N`c ,N~
NC
t2 ~CN N~ CH SO CH2 - cH2~cNcN
NC~C~ CH2--CH2--SOrcH2 - cH2H~N
21 O.Z. 0050/42225
Example No,
NC~ CH 2--CH 2--SO 2--CH 2--CH 2 ~CIY
NC~N I N1CN
~CH 2~CH 2 - CH 2 - ISI - CW 2--CH 2~CH 2~$3
H5C2 C2H5 H5C2 C2H5
CN CN
NClN 1l o NlCN
16 ~3~O--C--( CH 2 ) 4--C--O~3
H5C 2 C 2HS H5C 2 C 2H5
CN CN
NCJ~N R 1l NlCN
17 (~CH 2~C--( CH 2 ) 4-C~CH 2~3
,N~,N~
H5C 2 C6H13 H5C 2
18 NC~ N`C2H5 R H5 IC~_CN
- NC CH 2--CH 2~C~CH 2--CH 2 CH 3CN
CN H5C 2 CN
NC~< ~--N~C2HS ,1~CN
H3C CH2--CH2~1CH2) 2~CH2 - CH2 CH3CN
CN H~C 2 CN
NC~( ~--N~C2H5 8 N~N~CN
H 3C CH Z--CH 2~C~CH 2--~H 2 CH 3
.'''''' : .
2 ~
22 0 . z, 0050/4222
Exampl~3 No.
C~ IC2H5 H3C CH3
21NC-4/ ~ N-CH2-CH2-SO2-CH2-CH2-N ~ CH3
CN ~ CN
H3CCOHN
NC CN
C~3_ IC2H5 H3C CH3
22NC-~/ ~ N-CH2-CH2-SO2-CH2-CH2-N ~ CN
NC CN
H9C402C ~ CN CH3 CH3 NC ~ CN
23 ~ CN
H3COCHN Nl'~`HCH3 H3C-~N,~ NHCOCH3
CH2--~H2--S02 CH2--CH2
H13C602C ~ CN CH3 CH3 NC~r~CN
24 N ~ ~ CN
H3COCHN~ ~ ~ CH3 H3H,~7,1~_~1~CH3
CH2 -l~H2 - so2 - cH2 - cH2
H H CH3
25NC--4 ~ N-CH2-CH2-SO2-CH2-CH2-N ~ CN
CN NC
I~_CH2-CH2-502-CH2-CH2 N ~ ~-CN
CN NC
C 2U4CN C 2H4CN
27NC ~ N--CH2--CH2--O-CH2--CH2--~ ~CN
CN NC
,~ . , .
'
2 ~
,
23 0 . Z ~ 005~/42225
Example No.
CN C2H5 HgC4 CN
28 ,~=N~N / ~CN
~ CH2--CH2--0--(CH2) 2----CH2--CH2 CH3
CN
CN C 2H5 H7C 3 CN
29 ~=N~3N N~N=~
O~N H3C CH2--CH2--0--(CH2) 2----CH2--CH2 CH3 N02
CN C4H9 HgC4 C02C4Hg
~CN~3N 8 ~N~Na~
H9C402C CH2--CH2--o--C~30--CH2--CH2 co2C4Hs
CN C4Hg HgC4 CN
31 ~=N~3N~ 1l / ~N=~
~ CH3 (CH2--CH2) 2--O--C--O (CH2--CH2) 2 CH3 ~
N02 N02
.
