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Патент USA US2118916

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Patented May 31, 1938
Julius Drucker, Leverkusen-I. G. Werk, Germany,
assignor to I. G. Farbenindustrie Aktiengeselb'
'schaft, Frankfort-on-the-Main, Germany
No Drawing. Application October 22, 1936, Serial
No. 107,021. In Germany October 14, 1033
_ 3 Claims.
(01. 134-58) ’
which is preferably done by the addition of a
This invention relates to improvements in ti
tanium-containing pigments, more particularly
strong acid.‘
it relates to a process of preparing such pigments
I The expression "strong acids” according to
- by heating ‘titanium-containing compounds, such
Falkenhagen, “Elektrolyte" Leipzig (1932), pages
4 and 5, is intended to include such acids which 5
as titanium hydrate underpressure in the pres
ence of water and strong acids.
already in strong concentrations are dissociated ‘i
to more than one half. Strong acids of the said
It is known that the process of calcination
usually employed in the manufacture of titanium
pigments, such as pure titanium dioxide or mixed
from titanium dioxide and barium sul
19 pigments
fate, calcium sulfate, zinc oxide etc., can be re
kindare perchloric acid, hydrochloric acid, hydro
bromic acid, hydriodic acid, nitric acid, sulfuric
acid, hydro?uoric acid,'?u'osilicic acid and all or- .10
~ganic sulfonic acids- The pérchloric acid partly
decomposes to hydrochloric acid under the condi- placed by the precipitation of the pigment at ele
vated temperature while applying superatmos , tions of pressure heating; the ‘same holds true tor
pheric pressure or also by treatment of the crude the organic sulfonic acids which form sulfuric‘ acid.
That is to say these acids only act insofar as hy- 15
precipitate with liquid water under elevated pres
drochloric‘ or sulfuric acid are formed on decom-
sure. But even if‘ this heating treatment is ef
fected in the neighborhood of the critical tem
perature of the water at about 370° C.,'" the cover
Very good results are obtained by applying
ing power and the tinting strength of the pig-' from 1/.100 gram equivalent of acid to 2 gram
equivalents of acid calculated upon one liter of 20
20 ments obtained are in no way satisfactory.
'I have now found that pigments displaying good "solution. The pigment obtained in accordance
_ covering power-and tinting strengthv are obtained
with this process immediately ,after the treat- '
- when the'heating of the crude pigment obtained
ment described is soft and smooth and consists
sure corresponding to the vapor pressure of‘the
liquid at the temperature indicated is effected in
manycases the addition of alkali metal halides,
for instance, common salt‘and potassium bromide
are of favorable in?uence on the pigments in par
of particles of a size ?t for use in paints and
, by hydrolysis of titanium salt solutions to a tem
‘perature of 250—370° .C., under at least the pres- _ the like without. the necessity of grinding. In 25"
the presence of a small amount of a free strong
_ '
acid. I have also found that by the presence of a “ticular their oil alis'orption.
30 small amount of strong acid the temperature and ' . The invention is further illustrated by the fol- 30_
lowing examples without being restricted thereto:
the time required for obtaining a de?nite tinting
Example 1.-"—19i) parts by weight of titanium ‘ -
strength are considerably diminished and that
also other technically important‘qualities, for in
tetrachloride are introduced into 1000 parts by
weight_of an aqueous solution containing 160
stance, the oil absorption, are improved to a
marked extent.
‘Free strong acid can either‘ be brought into
the reacting solution from which the crude pig
__ ' ment is obtained from the beginning, or the re
acting substances can be_ so selected that the
small amount of strong acid is formed during
the preparation of the crude pigment, or the
strong acid can also be added to the suspension
of the crude pigment in water which is to be
subjected to the heating under pressure, -;or it
can be added to the suspension during the heating'
under pressure, or it can be formed during the
parts by weight of sodium hydroxide and 130 35'
parts by weight of sodium chloride while stir
ring and cooling in such a manner that the tem
perature of the solution during‘the precipitation
‘does not essentially exceed 5°. C. This suspension
of ?nely divided titanic acid is acidi?ed with 85 40
parts by weight of 20% hydrochloric acid and is
then heated to about 360° C. under a pressure of
200 atmospheres and maintained at this tempera
ture'and this pressure for 30 minutes. Then the
suspension is_ cooled and the titanium dioxide 45
formed is converted into the ?nished pigment by
?ltering; washing and drying. The ?nished pig
ment is distinguished by a good covering power,
The maintenance of a de?nite hydrogen "ion. lightness and whiteness and has a low oil ab—
50 concentration in the acid range in the reaction sorption number.
mixture in?uences the qualities of the pigment . Example 2,-800 parts by weight of the washed
-to a Iarreaching extent. If; for instance, pig-. and filtered product as is obtained by hydrolysis
ments of the highest tinting strength- and cover
of titanium sulfate solutions containing iron and
ing power are to be produced, a distinct acidity
containing about 500 parts by weight of titanium -
should be maintained in'the reaction mixture dioxide and about 35 parts by weisht of ‘S0: in 66
the form oi’ titanium suliate, are suspended in
a solutionloi ‘18 parts by weight of sodium-hy
parts by weight of 20%» ?uosilicic acid and 1':
parts by weight oi para-toluene sulionic acid.
droxide in 400 parts'by weight of water and
The single batches are further treated as in
heated to about 360' C.‘under a pressure 0! 210 ' dicated in Example 1. In this manner soit pig
atmospheres for one hour. Thereupon the reac
ments of very good coloring power are obtained.
is cooled, the precipitate is sepa
whiteness and lightness of the pigments are very
rated from the solution, washed and dried. It
in the drying process any caking has occurred,
the caked lumps can be readily broken up by a
good with the exception oi the pigments treated‘
with hydro?uoric acid and ?uosilicic acid; they
show a blue-grey tint, the pigment treated with
simple crushing. This caking is din'erent from para-toluene sulionic acid has grey tint caused
the sintering of the pigment particles occurring a by the precipitating carbon.
in the calcining process, since after calcination
This is a continuation in part of our co-pending
the sintered pigment must be ?nely ground. ,
application for Letters Patent Serial No. 8,599.
Example 3.-180 parts by weight of titanium illed Feb. 14', 1935.
15 tetrachloride are introduced into 1000 parts by "
I claim:-
weight 01' a solution containing ,160 parts by
1. The process at preparing titanium-contain
weight of sodium hydroxide while stirring and ing pigments, which comprises hydrolyzing an
cooling in such a manner that the temperature ' aqueous solution containing a titanium salt at a
of the solution during the precipitation is main
temperature not exceeding the boiling point 01'
~20 tained at 30 to- 40° C. The sludge obtained is the solution at atmospheric pressure and then
treated with son-inch of hydrochloric acid that
the liquid contains still 11, moi. of hydrochloric
acid per liter after heating under pressure as
described in Example 2. The pigment is treated
as indicated in Example 2.
Example 4.-190 parts by weight of titanium
tetrachloride are introduced at 0-50’ C. into 1000
precipitated '- titanium-containing
crude Pigment in the presence of an aqueous
solution containing a tree strong acid to a tem
perature of between about 250 and about 3'10‘ C.
under at least the pressure corresponding to the
vapor pressure of the liquid at the temperature
parts by weight of water while stirring and cool
2. The process of preparing titanium-contain
ing.‘ The clear solution obtained is evaporated ing pigments, which comprises hydrolyzing an
whereby titanic acid is precipitated. The evapo
aqueous solution containing a titanium salt at
ration is continued until the sludge formed still a temperature not exceeding the boiling point
contains 15- parts by weight oi hydrochloric acid. of the solution at atmospheric pressure and then
Then the sludge is suspended in"500"parts by heating the precipitated titanium-containing
weight of water and heated underv pressure and crude pigment in the presence of an aqueous
solution containing from 1/100 to, 2 gram equiva
iurthertrea'tedas described in ‘Example 2.
The "pigments obtained in accordance with lents of a tree strong acid per ‘liter to a tem
Examples 2, 3 and 4 are of excellent tinting ' perature of between about 250 and about 370° C.
strength and covering power, great soitness and under at least the pressure corresponding-to the
have a low oil absorption number.
40 ,
vapor pressure of the liquid at the temperature
Example 5.--190 parts by weight of titanium
[tetrachloride are introduced into a solution of ,
180 parts by weight oi sodium hydroxide in ‘1000
parts by weight of .water while stirring and cool
3. The- process of preparing titanium-contain- ‘
ing pigments, which comprises
aqueous solution containing a titanium salt at a
ing, an that the precipitation temperature does . temperature not exceeding the boiling point ‘oi-I
45 not essentially exceed 5’ C. and that no vapors the solution at atmospheric pressure and then .
' of hydrogen chloride or titanium tetrachloride heating the precipitated titaniumecontaining
escape. 100 parts by weight each oi’ the said
suspension of iineiy divided titanic acid or tita
nium dioxide are treated with 6.4 parts by weight
of 50% nitric acid, 8.5 parts by-weight oi'"2_0%
hydrochloric acid; 20‘parts by weight oi 20% by
acid._5 parts by weight or 50% ‘sulfuric
crude pigment in the presence of an aqueousv
solution containing from H100 to 2 gram equiva
lents-oiaireestrongmineral acidperliterto
a temperature of between ‘about 250 and about
v3'10’ C. under at least the pressurecorresponding
'to the ‘vapor prasure oi’ the liquid attire-tem
parts by weight of. 20% hydro?uoric acid, :1
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