Note: Descriptions are shown in the official language in which they were submitted.
10~ 7l~/~ 0?~
7Q~
The present i.nvention relates to a process for the pre-
paration of disperse dyes having good pri.nting properties for
transfer printing.
In heat transfer or thermoprintingt disperse dyes havingr
sufficient subl;mation capability are worke~ -to printing
pastes using binders a~d organic sol~ents, the so-called
varnishes, or water and are printed on suitable paper accor-
ding to known printing processes, such as gravure pri~ting,
offset printing or flexographic printing.
The predominant process is gravure printing in which
anhydrous printing inks are used. Under the action of heat,
the di.sperse dyestuff is transferred from the paper to the
polyester fabric or to a fabric made of other synthetic fibers.
The disperse dyestuff can also be transferred from paper to
blended fabrics, for example, polyester-cotton blend, provi.ded
that the portion of synthetic fiber in the blend is high enough.
For the preparation of print:ing inks, there may be used
pulverulent, pure disperse dyes or disperse dyes mixed with
suitable diluents, for example natural or synthetic resins or
cellulose derivatives. In this case, it is not necessary that
the disperse dyestuff is as finely divided as it is required
for its usual fields of application where the fine division
required is only achieved by sand or pearl grinding in the
presence of di G persing agents. The fine division necessary
for the use in printing inks for heat transfer printing i.s
achieved, for example, by grinding a dried, pure disperse
dyestuff in a pin mill. The mixing agent to be addcd can
either be g.~ound at the same time in the pin mill or mixed
29 after gr;.nding wi-th the ground disperse dyestuff in the
- 2 -
llOl 7~lJ~ 0-,7
~U ~ ~7 ~ ~
desired ratio. T~le grain sizes achieve~ in the pin mill are,
in general, about 10 to 100 times larger than tnose achieved
by pearl grinding. A similar degree of fine division is achieved
by treating an aqueous suspension of a disperse dyestuff, op-
tionally in the presence of the desired diluent, with a dis-
solver, a turbulent mixer or homogenizers having a similar
effect or also with a ball mill. Very suitable preparations
are a]so obtained by treating a mixture o~ dyestuf~ and diluen-t
in a kneader.
~owever, practice shows, that some disperse dyestuffs
assumed to be suitable for heat transfer printing on account
of their relatively poor fastness to sublimation, cannot be
used because the anhydrous gravure print:ing inks prepared with
th~se dyestuffs are not sufricierltly stable in their vi3cosity
and more or less rapidly after~thicken until they become un-
usable, or they are, a priori, in the form of a paste uncapable
of flowing which can, therefore, not be processed. This un-
desired property of some of the disperse dyestuffs supposedly
suitable for transfer printing, cannot be overcome even by
modifying the binder or varnish preparations. However, in
gravure printing mainly carried out in practice, a printing ink
of good flowability is absolutely necessary. Moreover, such a
printing ink should retain its flowability over a longer period
of time, at least for 4 weeks, for only under these conditions
rational working is possible.
The present invention provides a process for the pre-
paration of disperse dyestuffs which yield printing inks of
suitable and constant viscosity for printing transfer printing
29 paper according to the gravure printing process, which process
-- 3 --
~34~7~
comprises treating such disperse dyestuffs - which when obtained according
to usual processes yield printing inks having viscosity properties unsuit-
able for gravure printing - in an aqueous, water-containing or water-free
liquid medium in which the disperse dyestuff is essentially insoluble pre-
ferably at a temperature within the range of from 50 to 180C, most prefer-
ably from 80 to 130C, optionally while stirring.
The process of the invention can be carried out using an
already isolated, purified and, optionally, dried disperse dyestuff which
was prepared according to the usual methods. Another possible method is
to use directly an aqueous, water-containing or water-free suspension formed
in the usual preparation method, the addition of one or several organic
solvents being a possible advantage. Suitable organic solvents are those
in which the dyestuffs shows a solubility as low as possible. Preferably,
hydrocarbons are used, especially aliphatic hydrocarbons, but also cyclo-
aliphatic or aromatic hydrocarbons which may be halogenated completely or
partially, such as petroleum ether boiling within the range of from 50 to
about 200C, tetrachlormethane, perchlorethylene, chlorobenzene, dichloro-
benzenes, toluene and xylene. Furthermore, solvents miscible with water are
used, preferably in mixture with water, such as dimethyl formamide, alkanols
of up to 6 carbon atoms, lower dialkyl ketones, such as acetone, dimethyl
sulfoxide and lower alkane carboxylic acids, such as acetic acid. The
period of the treatment according to the invention at a temperature within
the range of from 50C to 180C depends on the nature of the disperse dye-
stuff, however, at the temperatures preferably applied, the period required
is within the range of 30 minutes to 10 hours. The pH-value of the aqueous
medium may vary within
-- 4 --
~,
~I OE 71~ C) 5 7
1~4~8
wide limits 5 but it is, preferably to be he]d withiIl the range
of 5 to 8, so that sensitive substituents optionally present
in the disperse dyestuffs remain unchanged.
In the process according to the invention for the pre-
paration of disperse dyestuffs which yield printing inks of
suitable and constant viscosity for the printing of transfer
printing paper according to the gravure printing process 9
the crystal modification can be chang~ed, for example, as
described in German Offenlegungsschrift No. 1,619,535, which
is, however, no prerequisite for the disperse dyestuffs
treated according to the invention to yield gravure printing
inlcs of suitable and constant viscosity.
The viscosity of the printing inks described in the
following ~xamples is characterized by the "flow time" meas~
ured according to DIN (German Industrial Standard) 53 211
which they need to run out of a DIN beaker ("Fo d cup") pro-
vided with a nozzle of 4 mm diameterO In the case of the
anhydrous printing inks obtainable according to the invention
this time is less than 35 seconds, preferably 25 seconds or
less.
The binders used in the Examples for the preparation of
the printing inks have the following composition-
Binder A: 12 ~o of ethyl cel1ulose N 7
3 % of ethyl cellulose N 22
10 % of ethylene glycol monoethyl ether
25 % of ethyl acetate
50 % of ethanol
Binder ~: 12 p of ethyl cellulose N 7
29 3 % of ethyl cellulose N 22
HOE 74/~
~)4~7~
10 Cj~ of oth-ylcne glycol monoethyl ether
75 /6lo of ethanol.
"Ethyl cellu1ose N 7" and "N 22" are ce]lulose et}lyl
ethers an~ comlnercial products of ~Iessrs. Hercules Inc., 1~
mington~ Dela. 19~,9~/USA. The numbers indicate the average
viscosity of a 5 ~p solution in a 4 : 1 mixture of toluene and
ethanol at 25C in cP.
The cellulose acetobutyrates used in the ~xamples are
commercial produc-ts of ~lessrs. Eastman Kodak Co., Kingspolt,
Tenn. 37662/USA and are distinguished as follows:
Cellulose acetobu~ra-teC~, 551-0.2: acetyl content: 2.0 'p
butyryl content: 53 ~j',
Cellulose acetobutyrate CA~ 3~1-2: acetyl content: 13.5 /'
butyry?. content: 37 ~'
The process of the invention is preferably applied for
dyestuffs of the general formula
X O 0~
A ~ Hal~_ ~
y 0 NH2~aRa
in which one of the radicals X and Y is a hydroxy group and
the other one is a radical of the formula -NH2 bR'b, R and R
being-preferably identical - alkyl groups o~ 1 or 2 carbon
atoms, preferably methyl groups, Hal stands for chlorine atoms
or, preferably, bromine atoms,-~is a number of O to 2,
preferably 1, and a and b each is a number from O to 2, a ~ b
gi~ing O to 3, preferably 0.5 to 2, especially 0.5 to 1~
~9 Such dyestuffs are, for example, described in German Patents
-- 6 --
~101, ~ O `' ~
1'~4~7~P8
Nos. 1,029,506, 1,150,li77 and 1,162,961.
The dyestuffs rererred to in tlle Examples are prepared a5
follows; the parts bei.ng by weight:
(1) German I'atent N'o. 1,162,961, ExaMple 2)
27 Parts of 4,~-diamino-1,5-dihydroxyanthraq1linone were
dissolved at 40C in 100 parts of 100 % sulfuric acid
("monohydrate"), 10 parts of polyphosphoric acid we~-e
added and then, 3 parts of para~formaldehyde were intro-
duced at 30 C while stirring. The mixturc was stirred
for 8 hours at 30 - 35C and the reaction mixture was
carefully poured onto ice. The dyestuff obtained ~a~
suction-filtered and washed un-til neutral.
(2) (German. Patent No. 1,150,1~77, Example 1)
14 Parts of 1l~8-diamino-1~5~-dihydro~yanthraquiIlone were
dissolved at 40C in 68 parts of 100 o,h sul.furic acid, the
solution was allowed to cool and 1.5 parts of paraform-
aldehyde were introduced portionwise while stirring so
that the temperature did not exceed 35C. Then, the
mixture was stirred for 4 to 10 hours at 30 to 35C and
carefully poured onto ice. The precipitate was suction-
filtered and washed until neutral. After drying, 14.5
parts of a blue dyestuff were obtained.
(3) (German Patent No. 1,029,506, Example 2)
27 Parts of 4,8-diamino-1,5-di.hydroxyanthraquinone and
10 parts of boric acid were dissolved in 250 parts of
100 % sulfuric acid to ~hich solution 0.1 part of iodine
and 10 parts of bromine were added. Then, the solution
was st;rred at 50C until the bromi.ne had been consumed,
29 then the reaction mixture was poured onto ice, the
-- 7 ~
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1¢~4~37~8
preciI)itate was suction-filtered and washed un"il neutral.
So, 35 parts of a blue d~escuff were obtained which con-
tained about 25 % of bromine.
(4) (German Patent ~o. 1,162,961, ~xample 1)
27 Parts of a miYture of 55 parts of 4,8-diamino-1,5-di-
hydro~y-anthraquinone and 45 parts of 4,5-diamino-1,8-di-
hydroxyanthraquinone were dissol~red at 40 C in 100 parts of
100 G/~ sulfuric acid, the mixture was allowed to cool and
into the solution obtained a previously prepared mixture
of 100 parts of 100 o~h sulfuric acid, 3 parts of paraform-
aldehyde, 5 parts of phosphorous pentox:ide, and 20 parts of
N-methylacetam~de was added dropwise at 30 -to 35 C wllile
stirring. Then, the solution was again stirred at t~lat
temperature for 4 to 10 hours and the reaction IniY.ture was
caref`ully put onto ice. The precipitate obta:ined was
suction-filtered and washed until neutral.
E X A M P I E S:
E X A M P L E
10 Parts of the disperse dyestuff (I) in the form of 30 parts
of the fi]ter cake, which had been washed until neutral were
suspended in 80 parts of water and heated to 130C for 1 hour
in the stirring autoclave. After cooling, 17.3 parts of cellulose
acetobutyrate CAB 551-0.2 and 1.3 parts of cellulose aceto-
butyrate CAB 381-2 were added to the dyestuff suspension and
passed twice through a colloid mill. Suction-filtering and
drying in the vacuum drying cabinet at 60C followed. The dry
filter cake disintegrated to loose granules, 5 parts of uhich
were worked into 95 parts of binder A in an attritor.
29 Immediately after its preparation, this printing ink showed a
5 7
i341~7~?~3
flow time of 1~ seconds and. Was excellently suitable for
printing heat trans~`er printing papers according to the gravure
printing process. 4fter a 7 days~ ~torage at 50 C, which
approxinlately correspond.s to a storage of 4 we~ks at room
temperatl~re, the flow time of the printing ink was 19 seconds.
However~ when the pr;ntillg ink was prepared from a pre-
paration having the same composition and bei~g prepared. in the
same manner, but which conta.ined the d.i.sperse dye (1) llOt being
after-treated in the autoclave, -the flow time of the printing
ink was 25 seconds immediately after the preparation of the
pri.nting ink. Afte3- a 7 days' stor~ge at 50C tlle printing il-lk
.had completely thickened., could not flow any longer and had
become unusable.
E X A M P L E 2
10 Parts of dry dyestuff (2) were heated in 100 parts of
perchloroethylene to 100C for 2 hours while stirring. Then,
the perchloroethylene was eliminated by steam distillation,
the dyestuff was suction-filtered from the aqueous suspension
obtained and dried at 60C in vacuo. This dyestuff was ground
in a pin mill. 1.75 parts of the pulverulent dyestuff were
processed with 98.25 parts of binder A in an attritor to yield
a printing ink which showed a flow time of 24 seconds and
excellently suits for printing heat transfer paper according
to the gravure printing process. After a storage time of 7 days
at 50C, the viscosity of the prinling ink re~lained unchanged.
However, when 1.75 parts of dyestuff (2) not being *reated
with perchloroethylene were used for the preparation of the
printing ink the resulting printing ink showed a flow time of
29 26 seconds. After a 7 days~ storage at 50C, the printi.ng ink
- 9 _
~~_ 7~1 ` 0-~7
4f~7~'B
had completel.)~ thickened. Th~ viscosity could not be de-
termined any longer.
E X A M P L ~, 3
.
10 Parts of disperse dye~stuff (2) were introduced in the
form of the dri,ed filter cake in a mix-ture of 90 parts of water
and 10 parts of dimethyl formamide and heated to 100C fo-r
l~ hours. Then, the dyestuff waS suction-fi,ltered, washed alld
dried at 60C in vacuo. 7.5 par-ts of this dyestuff were grc,und
with 16.4 parts of cellulose acetobutyrate CAE 551-0.2 arld
1.1 parts of cellulose acetobutyrate C~B 381-~ iIl a pin mi.ll,
After incorporating 5 parts of this preparati.on into 95 par-cs
of binder B by means of` a usual dispersing aggregate, the
printlng ink showed a flow t:ime of 25 seconds ~nd s~ited very
well for printing heat transfe:r paper accordiIlg to the gr3vure
printing process. After a storage time of 7 clays at 50C, the
viscosity remained unchanged. ~lso :in the ,following storage for
6 weelcs at room temperature, the viscosity of this printing ink
did not change.
However, when the printing ink was prepared by means of
a preparation having the same composition with the difference
of containing a dyestuff (2) which had not been after-trea-ted
~rith water-containing dimethyl formamide5 the flow time was
45 seconds. Already after 24 hours, this printing ink had
thickened to be completely unusable and the viscosity could
not be determined any longer.
E X A M P L E 4
10 Parts of dyestuff (3) in the form o`f 35 parts of the
filter cake washed until neutral were heated in 75 parts of
29 water in the autoclave to 130C for 3 hours while stirring.
- 10 -
--o~7~ o >z
~4~
~fter cooling, t~-,c dyestuff was suction-f;.l-tered, dried at
60 C in vacuo and pulverized i~ a pin mill. ~sing 1.75 parts
of this dyestuff powder and 98.25 parts of binder E, a printing
ink was obtained in the attritor having a flow tim~ of 17
seconds which excellently suited for prin-ting heat transler
printing paper according to the gravure pri.nting process.
After a storage period-of 7 days at 50C the printing ink hacl
a flow time of 24 seconds.
However, when the printing inlc was prepared using the
dye.stuff (3) which had not been treated in the autoclave, dried.
and ground i.n the pin mill, the printi.ng in]c thickened so much
a]ready during its preparation in the attritor that it could ILOt
be used at all. The viscosity could not be meas1lred.
E X J'~ ~ P L E 5
10 Parts of the disperse dyestuIf (4~ in the form of the
filter cake washed neutral and. dried were heated to 110 C
during 2 hours in 100 parts of chlorobenzene, while stirring.
Then, the chlorobenzene was eliminated by steam distillation.
18.6 parts of rosin (colophony~ were added to the aqueous
dyestuff suspension, the whole being passed through a colloid
mill.
After suction-filtering and drying at 60C in vacuo 9 a
preparation in the form of loose granules was obtained.
5 parts of this preparation yielded, upon being worked into
95 parts of binder A, a printing ink of a flow time of
28 seconds which suited very much for printing heat transfer
printing paper according to the gravure printing process.
After a 7 days~ storage at 50C, the flow time was 32 second.s.
- 29 However, when the printi.ng ink was prepared using a
- 11 -
.
~I~JI~ ~/r~
preparat:ion of the same composition, wit}l the difference -that
it conta~ned l,-e i-uf~ ) which h~d not been treated with chloro~
benzene, the flo~.~ time was 41 secon(is. ~*ter a storage period
of 7 days at 50 C, th~t printing illlc had thickened ancl could
no longer be usecl for printing. Its viscosi-ty could no
7onger be deterniined.
E X A ~l P I E 6
. . _
- 10 Parts of dyestuff (3) in the I`orm of llo parts of filtecake were heated to 130 C for 1 hour in 70 parts of water ln
the autoclave, while stirring. After cool:ing, there were
added to the aqueous dyestuff suspension 17.3 parts of cellulosr-
acetobutyrate C~B 551-0.2 and 1.3 parts of cellulose aceto-
butyrate C~13 381-2 and the whole was ground in a colloid mill.
A~ter suc(:io~ i.ltering5 the fi~ter caXe ~a.s drled at 60C i~
vacuo. 5 parts of this dye~tuff preparation were incorporated
into 95 parts of binder A by means of an attritor~
The flow time of the printing ink was 21 seconcls. Af`ter
a storage period of 7 days at 50C, the flow time had not
changed and the printing ink still suited excellent;y for
printing heat transfer printing paper accordin~ to the gravure
printing process.
Even when the storage period was extended to seveIal week.s
at room temperature, the viscosi-ty did not increase.
When in the preparation of the printing ink a preparation
was used which had the same composition with the di~ference~
however, that it contained dyestuff (3) which had not been
treated in the autoclave, the flow time of ~the printing ink
immediately aIter preparation was 20 second~, increasing to
29 3~ seconds after a storage of 7 days at 50 C. The viscosity
~/
4~7 ~ 8
~ creasecl cluring su~secluent stolage a-t room temperature reach:ing
after a ~ days~ storage at ~0 (` and a 2 weeks~ s-torage at roo~
temperature a c~egree of viscosity that couicl not be determilJcd
any longer and the ~rintirlg ink was spoilt for use ln printin~r.
