Solids dispersions which can be easily distributed in hydrophobic and hydrophilic media and are stable to flocculation, and their use

Stable dispersions of solids, especially pigments, are obtained by distributing a solid having acidic groups on its surface in a liquid medium comprising an amine having at least one aliphatic chain of more than 5 carbon atoms, a non-ionic and/or an anionic surfactant having one or more aliphatic chains with a total of more than 5 carbon atoms and an organic water-miscible solvent. These dispersions are easily distributable in hydrophobic and in hydrophilic systems.

The present invention relates to dispersions, which are stable to 
flocculation, of solids which possess, on the surface, groups having an 
acid reaction, and to their use for tinting and/or filling hydrophobic 
and/or hydrophilic systems. Dispersions of solids which possess this 
surface property tend to flocculate particularly readily. This 
flocculation can take place during the dispersion process, or can take 
place during storage. However, it is frequently observed on stirring a 
solids dispersion of this type into media which are foreign to the system. 
These flocculation phenomena result in dispersions with a high viscosity 
and useless technological properties. 
It has been found that dispersions which have a high stability to 
flocculation both when incorporated into hydrophilic media and when 
incorporated into hydrophobic media can be prepared from solids which 
possess, on the surface, groups having an acid reaction. These dispersions 
according to the invention contain 
(a) solids with acid groups on the surface, 
(b) amines with at least one aliphatic carbon chain with more than 5 carbon 
atoms, 
(c) non-ionic and/or anionic surface-active agents with aliphatic carbon 
chains with more than 5 carbon atoms and 
(d) water-miscible organic solvents. 
The dispersions according to the invention preferably contain about 5-80% 
by weight of solid, 0.2-8, in particular 0.5-5, % by weight of amine, 
3-25% by weight of surface-active agent and 10-85% by weight of 
water-miscible organic solvents, and optionally water. In addition, 
preferred dispersions can contain 0.05-1% by weight of preservatives. 
The term "carbon chain" is to be understood as an uninterrupted arrangement 
of carbon atoms with single and double bonds, which can also be cyclic and 
can contain substituents, such as hydroxyl. 
All inorganic and organic solids which are essentially insoluble in the 
solvent system mentioned, which can be finely distributed and which 
possess, on the surface, groups having an acid reaction can be used for 
the new dispersions. Acid groups on the surface are in general found when 
the solids have a pH value of less than 7 in an aqueous suspension 
(according to DIN 53,200). Amongst inorganic solids, this reaction occurs 
in the case of oxides of metals of main groups 3 to 6 and of subgroups 4 
to 8. In general, it is caused by hydroxyl groups on the surface. Examples 
of suitable inorganic compounds for the preparation of the dispersions 
according to the invention are silica, alumina, antimony oxides, white 
pigments and colored pigments, such as titanium dioxide, iron oxide, 
chromium oxide and mixed oxides which contain metal oxides of this type, 
and solids which are coated with layers of oxides of this type. 
Further examples of solids which are suitable for the preparation of the 
dispersions according to the invention are carbon blacks and 
fine-particled organic polymer particles and pigment particles which, 
because of the manufacturing process, oxidative after-treatment or a 
surface reaction, carry acid groups, such as, for example, carboxyl, 
lactone, hydroxyl or sulfo groups. Carbon blacks on the surface of which 
acid groups can be easily produced by oxidation reactions are to be 
mentioned in particular. 
Preferred amines correspond to the general formula 
##STR1## 
in which R.sup.1 is an aliphatic, araliphatic or cycloaliphatic radica 
with a carbon chain of at least 5, preferably 10-25, carbon atoms and the 
carbon chain of which can contain one or more double bonds and also 
hydroxyl groups, and in which R.sup.2 and R.sup.3 are hydrogen atoms, 
aliphatic, araliphatic or cycloaliphatic radicals having a carbon chain 
with 1-30 carbon atoms, --(CH.sub.2).sub.n OH or --(CH.sub.2).sub.2 
NH.sub.2 groups, it being possible for n to assume values from 1-6. 
Examples which may be mentioned are hexylamine, cyclohexylamine, 
octylamine, decylamine, dodecylamine, tetradecylamine hexadecylamine, 
octadecylamine, octadecenylamine, eicosylamine, docosylamine, 
dodecylaniline, and derivatives obtained therefrom which possess alkyl, 
benzyl, hydroxy-ethyl or aminopropyl groups instead of both or one of the 
amino hydrogen atoms. Fatty amines and their derivatives are particularly 
suitable, such as, for example, cocoamine, laurylamine, cetylamine, 
stearylamine, tallowamine, oleylamine, stearylmethylamine, distearylamine, 
di-tallowamine, dimethyl-soyaamine, dimethyllaurylamine, 
laurylpropylenediamine, N-tallowtrimethylene-diamine, 
dihydroxyethyloleylamine and dihydroxyethylcocoamine. Free amines are 
preferably used; acids or further bases may be present, but in general 
this is not advantageous. 
Anionic and non-ionic surface-active agents which possess, inter alia, a 
medium-chain or long-chain aliphatic hydrocarbon radical are suitable for 
the solids dispersions according to the invention. Examples of non-ionic 
surface-active agents which have proved suitable are alkoxylation products 
of alkylphenols, fatty alcohols, fatty amines and fatty acids, in 
particular reaction products of nonylphenol, tributylphenol, coconut fatty 
alcohol, lauryl alcohol, stearyl alcohol and oleyl alcohol with 2 to 30, 
preferably 5 to 20 moles of ethylene oxide. Anionic surface-active agents 
which may be mentioned are alkyl-sulfates, alkylsulfonates, 
alkylbenzenesulfonates and condensation products of fatty acids and 
taurine or hydroxyethanesulfonic acid, as well as reaction products of 
ethoxylated alkylphenols and fatty alcohols with chlorosulfonic acid, 
especially lauryl-sulfates and dodecylbenzenesulfonates. The anionic and 
non-ionic surface-active agents can be used alone or as mixtures. 
Solids dispersions with particularly good properties are obtained if amines 
and anionic or non-ionic surface-active agents with the same or a similar 
aliphatic radical are employed for the preparation. 
Suitable solvents are organic compounds which are completely water-miscible 
or are water-miscible to a limited extent. Solvents which prevent or delay 
drying up of the solids dispersions are preferably used, such as, for 
example, glycols and acid amines, in particular ethylene glycol, propylene 
glycol, hexylene glycol, diethylene glycol, dipropylene glycol, 
polyethylene glycols polypropylene glycols, formamide and 
N-methylpyrrolidone. For the preparation of the dispersions according to 
the invention, they can be used alone or mixed with one another or with 
water. 
The dispersions are prepared in a manner which is in itself known, 
depending on the particle hardness of the solids employed, for example 
using dissolvers, rotator-stator mills, ball mills and pearl mills, in 
high-speed turbulent mixers or kneading apparatuses or on roll mills. 
Auxiliaries, such as, for example, preservatives, can be added to the 
dispersions during the dispersing process or thereafter. 
The solids dispersions according to the invention are distinguished by very 
good rheological properties and high stability on storage, even in the 
case of a high solids content. They can be distributed extremely easily in 
the most diverse hydrophilic and hydrophobic media without flocculation 
phenomena thereby occurring. If pigments are used as the solids, pigment 
toner pastes with a high tinctorial strength and brightness are obtained 
with the claimed compositions. 
In order to demonstrate the wide possibilities of application and the high 
stabilities to flocculation, in each case three media are chosen for test 
purposes from the numerous hydrophilic and hydrophobic media. This choice 
is only for illustration and is in no way a limitation of the universal 
use possibilities of the solids dispersions according to the invention. 
Test Media: (A) One test medium is an emulsion paint based on polyvinyl 
acetate, containing 20 parts of stabilized rutile pigment, 24 parts of 
extender pigments (predominantly dolomite), 40 parts of a commercially 
available polyvinyl acetate dispersion suitable for emulsion paints 
(.RTM.Mowilith DM2HB) and 0.16 part of a methylhydroxyethylcellulose which 
has an average viscosity of 2 Pas in a 2% strength aqueous solution at 
20.degree. C. Water and the customary stabilizing agents account for the 
remaining 15.84 parts. 
(B) Another is an emulsion paint based on acrylic resin, containing 20 
parts of stabilized rutile pigment, 24 parts of extender pigments 
(predominantly dolomite), 40 parts of commercially available acrylic resin 
dispersion suitable for emulsion paints (.RTM.Rhoplex AC34) and 0.33 part 
of a methylhydroxyethylcellulose which has an average viscosity of 4 Pas 
in a 2% strength aqueous solution at 20.degree. C. Water and the customary 
stabilizing agents account for the remaining 15.67 parts. 
(C) Exterior wall paint based on polyvinyltoluene/acrylate, containing 15 
parts of stabilized rutile pigment, 34 parts of extender pigments 
(predominantly dolomite), 7 parts of a commercially available 
vinyltoluene/acrylate copolymer suitable for exterior wall paints 
(.RTM.Pliolite VTAC-L), 14 parts of a 10% strength solution of a 
commercially available modified vinyltoluene/acrylate copolymer suitable 
for exterior wall paints (Pliolite AC-3) in a mixture of aromatic and 
aliphatic hydrocarbons, and 30 parts of a mixture consisting of 
stabilizing agents, chloroparaffin and white spirit. 
(D) Another is an air drying alkyd resin lacquer, containing 30 parts of 
stabilized rutile pigment, 37.5 parts of long-oil alkyd resins based on 
vegetable fatty acids and 32.5 parts of a mixture consisting of driers, 
stabilizing agents, white spirit and crystal oil. 
(E) Another is a black emulsion paint based on polyvinyl acetate, 
containing 0.7 part of furnace black, 1 part of stabilized rutile pigment, 
43.3 parts of extender pigments (predominantly dolomite), 40 part of a 
commercially available polyvinyl acetate dispersion suitable for emulsion 
paints (Mowilith DM2HB) and 0.2 part of a methylhydroxyethylcellulose 
which has an average viscosity of 4 Pas in a 2% strength aqueous solution 
at 20.degree. C. Water and the customary stabilizing agents account for 
the remaining 14.8 parts. 
(F) Another is a black air-drying alkyd resin lacquer, containing 5 parts 
of lamp black, 40 parts of a short-oil alkyd resin based on vegetable 
fatty acids and 55 parts of a mixture consisting of driers, stabilizing 
agents, xylene, white spirit and butylglycol. 
In order to test for suitability, the solids dispersions described in the 
Examples which follow are manually stirred into, in each case, a 
hydrophilic and a hydrophobic test medium using a glass rod provided with 
a rubber policeman. If the solids are colored pigments, the concentration 
of the solids dispersion is chosen so that the white pigment/colored 
pigment ratio in the colored test medium is 10:1 in the case of inorganic 
colored pigments and 50:1 in the case of carbon blacks. If the solids are 
white pigments, 10 parts of the solids dispersion are stirred into 100 
parts of the black-colored test media. After stirring in for 3 minutes, 
the test medium is applied onto white art carton using a film applicator. 
In order to test the stability to flocculation, after drying for a short 
period, part of the film is subsequently rubbed with a brush or with the 
finger. If a flocculation process took place on stirring the solids 
dispersion into the test medium, the flocculated pigment is at least 
partially de-agglomerized by the shearing forces exerted on the film. The 
surface which has been subsequently rubbed is then more deeply colored 
than the surface which has not been after-treated. This "rub-out test" is 
particularly suitable as a simple test method for tinting pastes. 
In the Examples which follow, parts denote parts by weight. 
The pH value of the aqueous solids suspensions are determined according to 
DIN No. 53,200, but polyethylene vessels were used in the determinations 
which follow. The shaking time was increased to 15 hours. 
Thus the determination was carried out as follows: 
1.0 g of the pigment sample is weighed into a 50 ml polyethylene measuring 
vessel which can be closed (sparingly wettable pigments being made into a 
paste in the measuring vessel with an amount of ethanol sufficient for 
wetting) and 20 ml of freshly distilled or completely desalinated water, 
at room temperature, which has been rendered free from carbon dioxide 
beforehand by boiling for a short time, are added. The measuring vessel is 
immediately closed, shaken vigorously for 15 hours and left to stand for 5 
minutes. The measuring vessel is then opened, the pH sensor (glass 
electrode single member measuring cell or glass electrode with a reference 
electrode) is immersed for one minute and the pH value is read off on the 
pH meter. At least two such determinations are carried out.

EXAMPLE 1a 
650 parts of a titanium dioxide pigment, which has been after-treated with 
aluminum compounds and silicon compounds and gives a pH value of 6 in an 
aqueous suspension, are stirred in portions, using a blade stirrer, into a 
mixture consisting of 20 parts of oleylamine, 80 parts of an adduct of 10 
moles of ethylene oxide onto 1 mole of oleyl alcohol, and 250 parts of 
diethylene glycol. This mixture is passed through a rotorstator mill until 
a particle fineness &lt;2.mu. is obtained. 
A pigment dispersion of excellent flow is obtained which can be very easily 
distributed free from specks in the test media E and F without the 
slightest flocculation phenomenon thereby occurring. 
COMISON EXPERIMENT 1b 
If the 20 parts of oleylamine in Example 1a are replaced by 20 parts of an 
adduct of 10 moles of ethylene oxide and 1 mole of oleyl alcohol, a highly 
viscous, thixotropic dispersion is obtained which can be distributed in 
test medium F only with great difficulty. The rub-out test shows 
significant flocculation phenomena. 
EXAMPLE 2a 
500 parts of iron oxide black, which gives a pH value of 5 in an aqueous 
suspension, are introduced in portions into a mixture consisting of 20 
parts of octadecylamine, 90 parts of an adduct of 15 moles of ethylene 
oxide and 1 mole of stearyl alcohol, 90 parts of an adduct of 5 moles of 
ethylene oxide and 1 mole of oleyl alcohol, 150 parts of propylene glycol 
and 150 parts of diethylene glycol, and the mixture is stirred, using a 
dissolver, down to a particle fineness &lt;2.mu.. 
The dispersion with very good flowability thus obtained can be particularly 
easily distributed in test media A and D, and leads to excellent rub-out 
tests in medium A and to good rub-out tests in medium D. 
COMISON EXPERIMENT 2b 
If the 20 parts of octadecylamine in Example 2a are replaced by 10 parts of 
an adduct of 15 moles of ethylene oxide and 1 mole of stearyl alcohol and 
10 parts of an adduct of 5 moles of ethylene oxide and 1 mole of oleyl 
alcohol, a thixotropic dispersion which flows poorly is obtained which can 
be readily distributed in test medium A but, as a result of severe 
flocculation phenomena, can be distributed in medium D only very poorly. 
EXAMPLE 3a 
A dispersion consisting of 500 parts of iron oxide brown which has a pH 
value of 4 in an aqueous suspension, 15 parts of cocoamine, 185 parts of 
an adduct of 10 moles of ethylene oxide and 1 mole of cocoalcohol, 149 
parts of dipropylene glycol, 149 parts of ethylene glycol and 2 parts of a 
fungicide is prepared according to Example 2a. 
In this manner, a dispersion with good rheological properties is obtained 
which can be particularly easily distributed free from specks in test 
media B and C without the slightest flocculation phenomenon thereby 
occurring. 
COMISON EXPERIMENT 3b 
If the 15 parts of cocoamine in Example 3a are replaced by 7 parts of 
dipropylene glycol and 8 parts of ethylene glycol, a dispersion is 
obtained which, in contrast to Example 3a, flocculates when stirred into 
test medium C. 
EXAMPLE 4a 
A dispersion consisting of the following components is prepared as in 
Example 2a: 300 parts of iron oxide yellow, which has a pH value of 5 in 
an aqueous suspension, 20 parts of coco-amine, 180 parts of an adduct of 
10 moles of ethylene oxide and 1 mole of coconut fatty alcohol, 250 parts 
of formamide and 250 parts of N-methylpyrrolidone. 
This dispersion possesses good rheological properties and can be easily 
distributed and has a high stability to flocculation in test media B and 
C. 
EXAMPLE 4b 
A dispersion with comparably good properties as that in Example 4a is 
obtained by replacing coco-amine by tallow-amine and replacing formamide 
and N-methylpyrrolidone by 350 parts of hexylene glycol and 150 parts of 
water. 
EXAMPLE 4c 
A dispersion with a particularly high stability to sedimentation is 
obtained if, in Example 4a, tallow-propylenediamine is used instead of 
coco-amine and the mixture of formamide and N-methylpyrrolidone is 
replaced by 200 parts of polypropylene glycol (molecular weight 750), 200 
parts of polyethylene glycol (molecular weight 200) and 100 parts of 
water. 
COMISON EXPERIMENT 4d 
By replacing coco-amine in Example 4a by 20 parts of an adduct of 10 moles 
of ethylene oxide and 1 mole of coconut fatty alcohol, a dispersion which 
has insufficient ease of distribution and low stability to flocculation in 
test medium C is obtained. 
EXAMPLE 5a 
300 parts of a lamp black, which has a specific surface area, measured by 
the BET method, of 47 m.sup.2 /g and a pH value of 4 in an aqueous 
suspension, are kneaded in a `Z` blade mixer for 1 hour, with the addition 
of 20 parts of stearylamine, 104 parts of sodium dodecylbenzenesulfonate, 
225 parts of ethylene glycol and 56 parts of water. The kneaded mixture is 
diluted by adding 145 parts of ethylene glycol, 148 parts of water and 2 
parts of a fungicide. 
The dispersion with very good flow prepared in this manner can be 
exceptionally easily distributed in test media A and C without the 
slightest flocculation phenomenon thereby occurring. 
COMISON EXPERIMENT 5b 
If the stearylamine in Example 5a is replaced by ethylene glycol, a 
dispersion with distinctly poorer ease of distribution in both test media 
is obtained. The rub-out tests show slight flocculation phenomena in test 
media A and severe flocculation phenomena in test medium C. 
EXAMPLE 6a 
220 parts of a channel black with a specific surface area, measured by the 
BET method, of 87 m.sup.2 /g and a pH value of 4.5 in an aqueous 
suspension, 10 parts of oleylamine, 160 parts of an adduct of 10 moles of 
ethylene oxide onto 1 mole of nonylphenol, and 137 parts of ethylene 
glycol are made into a paste and kneaded for 1 hour in a `Z` blade mixer, 
and the mixture is then diluted with 273 parts of ethylene glycol, 198 
parts of water and 2 parts of a fungicide to give a dispersion with very 
good flowability. 
This dispersion can be easily incorporated into test medium D and very 
easily incorporated into test medium A. The rub-out tests show a good 
stability to flocculation in medium D and an excellent stability to 
flocculation in medium A. 
COMISON EXPERIMENT 6b 
If the 10 parts of oleylamine in Example 6a are replaced by 10 parts of 
ethylene glycol, a thixotropic dispersion is obtained which has poor ease 
of distribution and low stability to flocculation in test media A and D. 
EXAMPLE 7a 
400 parts of a furnace black, which has been subjected to oxidative 
after-treatment and has a specific surface area, measured by the BET 
method, of 37 m.sup.2 /g and a pH value of 3 in an aqueous suspension, are 
stirred in portions into a solution of 15 parts of 
tallow-trimethylene-diamine, 50 parts of an adduct of 6 moles of ethylene 
oxide and 1 mole of tributylphenol, 50 parts of an adduct of 18 moles of 
ethylene oxide and 1 mole of tributylphenol and 2 parts of a fungicide in 
250 parts of ethylene glycol and 233 parts of water. This mixture is 
ground in a pearl mill, using 1 mm siliquartzite beads, until a particle 
fineness &lt;2.mu. is achieved. 
The dispersion thus obtained is distinguished by very good rheological 
properties, particularly good ease of distribution in test media B and C 
and good stability to flocculation in medium C, as well as outstanding 
stability to flocculation in medium B. 
COMISON EXPERIMENT 7b 
By replacing tallow-trimethylene-diamine in Example 7a by 15 parts of 
water, a paste is obtained which can be incorporated into test media B and 
C only with great difficulty. The rub-out tests show severe flocculation 
phenomena. 
EXAMPLE 8 
The dispersions described in the Table which follows are prepared, with a 
channel black which has been subjected to oxidative after-treatment and 
has a specific surface area, measured by the BET method, of 470 m.sup.2 /g 
and a pH value of 2.5 in an aqueous suspension, in a `Z` blade mixer. In 
addition to the substances listed in the Table, all the dispersions 
contain 120 parts of carbon black, 160 parts of an adduct of 10 moles of 
ethylene oxide and 1 mole of oleyl alcohol, 298 parts of water and 2 parts 
of a fungicide. 
The rheological properties of the carbon black dispersions and the ease of 
distribution and the resistance to flocculation of the carbon black 
dispersions in test media B and C are given figures of merit from 1 to 6: 
1=excellent, 2=very good, 3=good, 4=moderate, 5=poor and 6=very poor. 
__________________________________________________________________________ 
Resis- 
Resis- 
tance tance 
Ethy- Ease of 
Ease of 
to to 
Other lene 
Rheolo- 
distri- 
distri- 
floccu- 
floccu- 
Exam- 
Amine addi- glycol 
gical 
bution 
bution 
lation 
lation 
ple content tives content 
proper- 
in in in in 
No. parts 
Amine parts parts 
ties 
medium B 
medium C 
medium B 
medium 
__________________________________________________________________________ 
C 
8a -- -- -- 420 1 6 6 6 6 
8b -- -- 30% 380 6 5 5 5 5 
strength 
NaOH, 40 
8c 15 cyclohexylamine 
-- 405 5 4 4 4 4 
8d 20 octylamine 
-- 400 2 4 4 4 4 
slightly 
thixo- 
tropic 
8e 40 distearylamine 
-- 380 5 2 3 2 3 
8f 40 stearylmethyl- 
-- 380 2 1 2 2 2 
amine slightly 
thixo- 
tropic 
8g 40 dimethyl-(soya 
-- 380 3 1 2 2 2 
alkyl)-amine thixo- 
tropic 
8h 50 dihydroxyethyl- 
-- 370 3 1 2 2 2 
oleylamine thixo- 
tropic 
8i 40 oleylamine 
-- 380 1 1 1 1 2 
8k 40 oleylamine 
30% 360 2 1 1 1 2 
strength slightly 
NaOH, 20 thixo- 
tropic 
8l 40 oleylamine 
acetic 
370 2 1 2 2 2 
acid, 10 slightly 
thixo- 
tropic 
__________________________________________________________________________ 
EXAMPLE 9a 
200 parts of a silica, which has been obtained by flame hydrolysis and has 
a surface area, measured by the BET method, of 145 m.sup.2 /g and a pH of 
4 in an aqueous suspension, are introduced in portions into a mixture 
consisting of 40 parts of oleylamine, 160 parts of an adduct of 10 moles 
of ethylene oxide onto 1 mole of nonylphenol, and 133 parts of ethylene 
glycol in a `Z` blade mixer. After a kneading time of 1 hour, the kneaded 
mixture is diluted with 167 parts of ethylene glycol, 298 parts of water 
and 2 parts of a preservative. 
The solids dispersion prepared in this manner possesses excellent 
rheological properties. If some of this dispersion is stirred into 5 parts 
of the carbon black dispersion 8a, the ease of distribution and the 
resistance to flocculation of the carbon black dispersion are 
significantly improved. For this reason the silica dispersion is 
particularly suitable for letting down pigment dispersions. In addition, 
it can be used for wetting and dispersing solids, in particular pigments. 
COMISON EXPERIMENT 9b 
If the oleylamine in Example 9a is replaced by 40 parts of an adduct of 10 
moles of ethylene oxide and 1 mole of nonylphenol, a highly viscous, very 
thixotropic paste is obtained which impairs the technological properties 
of carbon black dispersion 8a when admixed to this dispersion.