Note: Descriptions are shown in the official language in which they were submitted.
1 ~6 ~ 1 ~
The invention relates to a process for conditioning a pigment
or disperse dye by treating the colourant with liquid ammonia.
The term "conditioning" is to be understood in this context
as meaning, in addltion to an improvement of the tinctorial
properties, also a possible conversion into another
m~dification.
Various processes for conditioning a pigment or disperse dye
in order to improve the tinctorial properties are already
known. One known method is to dissolve the colourant in an
organic or inorganic solvent and to precipitate it again
from the solution by cyrstallisation or precipitation. In the
same way, organic solvents are used which do not dissolve the
pigment, but produce the conditioning effects or modifications -
under the influence of time and temperature. Further known
methods of conditioning are those in which the pigment is
ground or kneaded
Japanese published patent application 25526/76 for example
describes a process for improving the tinctorial properties
of an isoindolinone pigment, especially the colour strength,
gloss and transparency, by dissolving the pigment in a mono-
or dialkylamine, precipitating it in the form of the amine
salt by the addition of water, cleaving the amine salt by
heating, and separating the amine from the pigment again. In
this process, the pigment is recovered in the starting
.~
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i~6813
modificatkn A changein ~e mod~i~tion,for example of the linear
quinacridone into the y-modification, occurs ho~ever by
treating the corresponding ~-form in accordance with the
process of Japanese published patent application 50699/65
with an aliphatic polyamine of the formula NH2(R-NH)nH,
wherein R represents a linear saturated aliphatic radical
and n is an integer from 1 to 3, at elevated temperature.
Compared with the process of Japanese published patent
application 25526/76, the process of the present invention
has the advantage that, without dissolving and precipitating
the pigment beforehand with water after the treatment with
liquid ammonia, another modification and improved application
properties of the colourant are obtained only by evaporating
the reagent; and the advantage compared with the process of
Japanese published patent applicat~on 50699/65 consists in
the fact that, for the treatment, liquid ammonia is used
instead of a polyamine and elevated temperatures are not
necessary in order to effect a conversion into another
modification or to obtain improved application properties. It
is surprising that, during the treatment with liquid ammonia,
such conversions occur even at low temperatures up to -77.7C.
Preferably, the pigments or disperse dyes to be conditioned
by the process of the present invention are those of the
isoindolinone, azo, metal complex, quinophthalone and
1 116 8 1 ~
quinacridone series, and, in the case of the conversion into
a modification, this latter can be either an already known
or also a hitherto unknown modification.
In the treatment with liquid ammonia, which can be carried
out optionally under elevated pressure and/or at elevated
temperature, the colourant is suspended in the reagent and
stirred therein This procedure can take both hours and
sometimes only minutes or seconds. In the conversion into a
modification, the completion of the treatment is oten
detectable by the change in colour. The conditioned colourant
is isolated by filtration and subsequent r~moval of the
ammonia by evaporation or by direct evaporation thereof.
Optionally, the colourant is partially or also completely
dissolved in the reagent. In this case, the reagent is remo-
ved by direct evaporation, whereupon the dissolved colourant
precipitates and is isolated If the colourant is only
partially dissolved, then filtration can first be carried out
and the two colourant fractions isolated separately fr~m the
filter residue or the filtrate Provided the presence of
small amounts of water and/or organic solvents does not
exert a negative influence on the conversion into the new
modification, these substances can also be tolerated. However,
the treatment is preferably carried out in the absence of
water and/or an organic solvent. The treated pigments are
often obt ined in such microcrystalline form that they are
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~168i3
amorphous in X-ray analysis By increasing the size of the
microcrystals,~ ~mpleby ~t~treatment with organic liquids,
they can be converted into a dimension in which the new
modification can be detected by X-ray diffraction analysis.
When incorporated in lacquers, the products obtained
according to the invention have an increased colour strength
and gloss c~mpared with the starting products. Furthermore~
in the course of the treatment pigments can be obtained in
a finer and more coarsely crystalline new, but unstable,
modification, compared with the starting form On account of
this instability, the starting modification is obtained again
on application, in fine or coarse crystalline form, depending
on the mode af application. This can result in an increase in
colour strength and gloss or in the hiding power.
The application properties of the pigments treated with
ammonia, for example in respect of the wetting power on
incorporation or the rheological properties, can often
generally be improved. The pigments can be inorganic and
organic pigments, for example of the class of azo, azomethine,
anthraquinone, phthalocyanine, nitro, perinone, perylene,
dioxazine, thioindigo, metal complex, quinophthalone,
isoindolinone or quinacridone pigments.
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1 ~16 ~1 ~
To improve the texture of the colourants treated according
to the invention, especially or incorporation in plastics,
it is possible to use assistants. Instead of using pure
liquid ammonia, it is possible for example to use a solution
of a suitable assistant in the liquid ammonia. When the
liquid ammonia is evaporated, this assistant precipitates
and coats the pigment, thereby improving the dispersibility
on application. Soluble resins or plasticisers,especially
sulphonamides, can be used as suitable assistants in the
liquid ammonia.
An improvement in the texture can also often be attained by
carrying out the process such that, after the conversion,
the liquid ammonia is only partially evaporated and the
residual ammonia-pigment suspension is diluted by addition
of an organic solvent or water and filtered and the pigment
dried. I water is used as diluent, resinic acids can
additionally be dissolved in the aqueous æmmoniacal pigment
suspension and the resin can be precipitated onto the pigment
by spray drying or by acidification, which in turn results
in an improvement in the texture.
The pigments are particularly suitable for pigmenting
material of high molecular weight, for example cellulose
et~ers, such as ethyl cellulose, nitrocellulose~ cellulose
acetate, cellulose butyrate, natural resins or synthetic
-- 6 --
1 ~16 8 1 ~
resins, such as polymerisation resins, polyaddition resins
or condensation resins, for example aminoplasts, especially
ure~/formaldehyde and melamine/formaldehyde resins, alkyd
resins, phenolic plastics, polycarbonates, polyolefins, such
as polystyrene, polyvinyl chloride, polyethylene, poly-
propylene, polyacrylonitrile, polyacrylates, polyamides,
polyurethanes or polyesters, rubber, casein, silicone and
silicone resins, singly or in mixtures. It is immaterial
whether the above compounds of high molecular weight are in
the form of plastic masses, melts or of spinning solutions,
lacquers, paints or printing inks. Depending on the end-use,
it is advantageous to use the pigments as toners or in
the form o preparations.
Throughout the following Examples the parts are by weight,
unless otherwise stated. The relationship between parts by
weight and parts by volume is the same as that between the
gram and the cubic centimetre. The starting pigments of the
Examples are known compounds. Wherever it is not quite clear
whether the modifications are hitherto unknown or known ones,
they are designated A and B and C to distinguish the
difference in the modifications.
.
~ ~16 8
Examples 1-19
stirring vessel cooled with dry ice is charged with
10 parts of the colourant to be treated (see $ubsequent
table) and about 120 parts by volume of liquid ammonia (from
a pressure flask). The mixture is stirred until the conversion
to the modification is complete, which takes about 4 to 60
~inutes The ammonia is then evaporated by heating and
any traces still remaining are removed in vacuo at 100C. The
ammonia-free conditioned pigment is pulverised. In addition
to the improvement in the tinctorial properties obtained by
the conditioning, the treated pigments also show another, in
many cases new, modification. This is evident from the
changed X-ray diffraction spectra. The test of the application
characteristics of the resulting modifications, which often
exhibit a change in shade compared with the starting colourant,
reveals in many cases colouristically interesting results and
often a positive change in the application properties. This
also applies in particular to those cases in which the
modifications obtained by the treatment with ammonia are
unstable, as illustrated in Examples 22 and 23.
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- 10 -
~116813
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_ 12 -
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- 14 -
1 1~6
Example 20
10 parts of the greenish-yellow pigment of the formula
~ C=u\Cll~
are treated in about 120 parts by volume of liquid ammonia
by the process described in Example 1. X-ray diffraction
analysis reveals that the resulting pulverised pigment has a
different crystal modification compared with the starting
fonm When incorporated into plasticised PVC rolled sheets,
the new modification gives colourations of better hiding
power than the starting form In addition to the change in
crystal modification, the treatment in liquid ammonia
produces a conditioning effect. Electron microscopic analysis
confirms the enlarging of the crystals by the treatment with
ammonia.
Example 21
10 parts of the yellow pigment of the formula
Cl CH3 Cl
Cl ~ N=N-~N-COHN ~ C0 ~ Cl
Cl CH3 CH3 bH3 Cl
1~16813
are stirred in an autoclave with 60 parts of liquid ammonia
at 50C for 1 hour. The ammonia is evaporated off a~
temperatures above 30C (valve opening on the autoclave).
Traces of ammonia still remaining are removed at about 100C
in vacuo. X-ray analysis reveals that the resulting pulver-
ised pigment has a crystal modification indentical to that
of the starting form. However, when incorporated into
plasticised PVC rolled sheets, the pigment treated with
liquid ammonia gives a colouration of substantially greater
hiding power and of excellent fsstness properties. This
property is attributable to the enlarging of the pigment
crystals effected by the treatment with ammonia.
Example 22
10 parts of the yellow isoindolinone pigment of the formula
O CH20 ~
0 ~ C14
- 16 -
~ 1~6 ~1 ~
are treated in about 120 parts by volume of liquid ammonia
by the process described in Example 1. X-ray analysis reveals
that, compared with the starting form (~-modification), the
resulting pigment has a different crystal modification, which
shall be designated as ~-modification. Further examinations then
showed that the ~-modification is unstable and, on application,
is converted again into the more stable a-startirg modifi-
cation, which has excellent fastness properties. However, in
comparison to the untreated pigment, lacquers coloured with
the ~-modification have a substantially higher colour
strength while retaining the excellent fastness propertles
(reconversion into the a-modification). This effect is
attributable to the fact that, in the conversion into the
modification effected by the treatment with liquid ammonia, a
comminution of the particle si~e has occurred. D~s can be cone~m~ ~y
electron microscope photographs. The conditioning effect
caused by the conversion of the modification in liquid
ammonia is observed to be particularly marked when the
pigment is incorporated in lacquers, especially when it is
incorporated in metallic pigmented paints. Up to now it has
not been possible to obtain analogous colourations of such
high colour strength and with these fastness properties by
conditioning the a-modification by the conventional known
methods, for example grinding operations.
_ 17 -
_. _
1 ~16 8
Example 23
10 parts of the a-modification of the pigment used in
Example 22 are well stirred in 120 parts by volume of liquid
ammonia for 20 minutes, whereupon, as described in E~ample 22,
it is converted into the fine-crystalline ~-modification
The ammonia is then evaporated to a volume of about 30 parts
by gently warming the stirring vessel. Then 100 parts by
volume of methanol are cautiously added dropwise The
ammoniacal methanolic pigment suspension is well stirred for
30 minutes and thè pigment is then filtered off and the
filter cake washed with methanol and dried, affording the
pigment in what X-ray analysis reveals to be the more stable
-modification
The unstable, fine-crystalline ~-modification was converted
again into the stable a-modification by stirring it in
methànol. The addition of solvent also effects a reduction in
the reagglomeration of the pigment particles as occurs in the
process variant described in Example 22 Not only is a high
colour strength on incorporation in lacquers thereby attained,
but also a good dispersibility when the conditioned pigment
is incorporated in plastics.
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1~16~13
Example 24
7 parts o~ the yellow pigment o~ the ~ormula
~ ~ 14
C14 0
and 1.8 parts of S~aybelite ~esin are stirred together for
about 20 minutes in about 100 parts by volume of liquid
ammonia. By cautiously warming the stirring vessel, the
ammonia is evaporated to a volume o about 30 parts. The
pigment suspension is then dilu~ed with 100 parts of water,
stirred or 20 minutes, acidified with conc. hydrochloric
acid at temperatures of 20C, stirred for 10 minutes and
fi~ ered The ~ er cake is washed neutral with water and
dried. The pulverised pigment, which is coated with
Staybelite)Resin and reduced by the treatment with ammonia,
gives very strong, brigh~ yellow colourations when incorpo-
rated in lacquers and readily dispersible yellow colourations
when incorporated in plastics.
*) trade mark
19 -
1~16f~
l~ample 25
10 part~s of the yellow pigment of the formula
CF3 H
Cl~ N'N-CH-COHN~NN~=
~-o
~CH3 H
are treated in about 120 parts by volume o liquid ammonia
by the process described in Example 1. X-ray and electron
microscopic analyse8 of the resulting pigment reveal no change
in modification, but a pronounced reduction in particle ~lze.
When incorporated for example in lacquers, it has in c~mpari-
son ~o the starting pigment a substantially higher colour
strength with equally good astness propertie9.
Ex~mple 26
10 par~s of the C.~, pigment Orange 59 are treated with
O.S parts of benzenesulphonic acid-N-methylamide (Dellatal *
MMA, available from Bayer), in about 120 par~s by volume of
liq~id ammonia by the process described in Example 1. The
benzenesulphonic acid N-methylamide dissolves in the liq~id
ammonia and precipitates on evaporation of the ammonia,
coating the pigmen~ particles.
*) trade mark
_ 20 -
,, ~
1~16813
When the resulting pigment is incorporated in lacquers it
gives strong, yellowish orange colourations of excellent
fastness properties as a consequence of the reduction in
particle size during the treatment with ammonia.
Example 27
a) 10 parts of the orange pigment (~-modification) of the
fonmula
H
- 02N ~ N=N-3H-COHN ~ ~ O
CH3 H
are treated in about 120 parts by volume of liquid ammonia
by the process described in Example 1, yielding a pigment of
extremely microcyrstalline structure, so that most samples
appear amorphous in X-ray analysis. In indiv~dual cases, lines
present in the X-ray diagram indicate a different crystal
modification (modification C) as compared with the starting
pigment. Incorporation in an alkyd/melamine stoving enamel
yields stronger colourations compared with the starting pigment.
b) 5 parts of the pigment obtained in a~ are stirred in
60 parts by volume of o-dichlorobenzene for 18 hours at
160-165C, then filtered off and dried, yielding the pigment
in a third crystal modification B. Incorporation of this
_ .. , ., ~
1 116 ~1 ~
modification in lacquers or plastics yields strong yellow
colourations of good fastness properties.
c) Repetition of the procedure described in b), but using
methanol instead of o-dichlorobenzene and stirring at reflux
temperature, yields the pigment again in the A modification.
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