Note: Descriptions are shown in the official language in which they were submitted.
2072332
Title: Dispersing agents, their use and solids coated therewith.
The present invention relates to dispersing agents or
their salts, on the basis of a compound having at least one
ring nitrogen-containing basic group, and the preparation of
such compounds.
The invention further relates to the use of the dispersing
agents and pulverulent or fibrous solids to be incorporated in
liquid systems, which solids are coated with such dispersing agents.
Powerful mechanical forces are required for introducing
solids into liquid media. This depends to a large extent on the
ease with which the solid can be wetted by the surrounding
medium and on the affinity to this medium. To reduce these
dispersing forces, it is customary to employ dispersing agents
which facilitate incorporation. These are in most cases
surface-active substances, also known as tensides, which have
an anion^active or cation-active and nonionic structure. These
substances are added in relatively small quantities, either by
direct application to the solid or by introduction into the
dispersing medium. The effort r quired for dispersion is
substantially reduced by such a tenside.
It is also known that these solids tend to reagglomerate
after the dispersion process, thus vitiating the effort
previously expended for dispersion and leading to serious
problems. This phenomenon is explained by London/van der Waal~s
forces by which the solids attract each other. TO overcome
these forces of attraction, it is necessary to apply adsorption
layers on the solids. This is achieved by using such tensides.
2072332
During and after dispersion, however, an interaction
between the solid particle and the surrounding medium takes
place and desorption of the tenside occurs, accompanied by its
replacement by the surrounding medium, which is present at a
higher concentration. This surrounding medium, however, is in
most cases not capable of building up such stable adsorp~ion
layers, and the whole system breaks down. This manifests itself
by a rise in viscosity in liquid systems, loss of gloss and
shift in colour tone in lacquers and coatings, insufficient
development of colour power in pigmented plastics, and decrease
of mechanical strength in reinforced plastics.
European patent application 154,678 discloses a dispersing
agent comprising the reaction product of a polyisocyanate
having a valence of from 2.5 to 6 with a monohydroxyl compound,
a difunctional component and a compound containing a basic ring
nitrogen.
Due to the nature of the compounds and the reactions
connected therewith, it is essential for the product to be
manufactured by a multistage method. With regard to the
production efficiency this is not desirable. Moreover, the
problem occurs that both the intermediate and the end product
are not very stable and tend to gelatinization.
More in particular, it may be noted that it iæ necessary
according to the known method to us~ ~ multistage process
wherein after stage 1, in which the polyisocyanate must first
be reacted with the monomer compounds, a difunctional compound
cannot be used until in stage 2. If this uneconomical process
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is not used and the components from stages 1 and 2 are
therefore reacted from the beginning, complications will occur
in process stage 3 to the extent of a substantial formation of
gel particles and a gelatinization of the entire mass.
The intermediate resulting from reaction stages 1 and 2, which
is reacted in stage 3 with compounds of formula III to obtain a
ready-for-delivery product, only has a very limited shelf life
(about 24 h) and is therefore not suitable for supply as a
basis for further addition reactions.
The products manufactured by the process described show a
marked tendency towards gelatinization in the third reaction
stage so that these reactions can only be effected in highly
diluted solutions, resulting in end products which only have a
relatively low solid content. The increase in solid by
subse~uent vacuum distillation is not possible in view of the
marked tendency of the product towards coagulation.
The known dispersing agents further have a compatibility,
a solubility and a dispersing activity which are not very good.
It is an object of the present invention to provide dispersing
agents which, as ccmpared with the known dispersing agents,
have improved properties, in particular improved compa~ibility
with binding agents, improved solubility and improved
dispersing activity.
It is further an ob~ect of the present invention to
provide dispersing agents which do not have the above
disadvantages with regard to their preparation or to a
substantially less extent, and which particularly result in
2072332
dispersions o~ solids which do not tend, or only to a minor
degree, to reagglomerate after the dispersion process.
It has now surprisingly been found that this problem may
be solved by means of the dispersing agents defined below.
The invention thus relates to dispersing agents or their salts
comprising
A the reaction product of one or more polyisocyanates having
an average functionality of 2.0 to 5, with
B at least a monohydroxyl compound,
C at least a dicarboxylic acid compound and
D a compou~d containing at least one basic ring nitrogen a~d
an isocyanate-reactive group, in which of the isocyanate groups
about 30-70~ are reacted with B and C together and about 30-70%
with D.
It has now surprisingly been found that the dispersing
agents according to the invention show a better compatibility
with, e.g., alkyd resins and oil-free polyester resins, a
better solubility and a better dispersing activity of different
pigments that are hard to stabilize.
The above advantages are very important in using these
binding agents. In consequence thereof, the binding agents can
be better used for the dispersion of pigments in binding
agents. More in particular, the better solubility offers the
possibility of using the dispersing agents in high-solids
lacquers because it is advantageous in such systems to use
fewer solvents.
When dicarboxylic acids are used instead of the known
di- and trimeric hydroxyl compounds, the following advantages
can be obtained in the preparation of the dispersing agents:
The laborious and uneconomical 2-stage process for preparing
the intermediate described in European patent application
154,678 can be carried out in one stage when using
dicarboxylic acids without the occurrence of gelatinization
with the reaction in the third stage.
The initial products manufactured with dicarboxylic
acids have a substantially improved shelf life (several
weeks) so that the most different end products can be
manufactured from an intermediate, also after a prolonged
intermediate storage.
In view of the low tendency towards gelatinization in
the third reaction stage, it is possible to manufacture end
products having an increased solid content, which is
advantageous in the manufacture of lacquers having a high
solid content.
Formulae 1 to 8 on the attached sheets of formulae
represent polyisocyanates suitable for use in the present
invention.
According to the invention a polyisocyanate having a
functionality of from 2,0 to S, preferably about 4, is used
in the dispersing agents. Suitable polyisocyanates are those
which may be obtained, e.g., by the addition of diisocyanates
to polyols, according to formula 1 of the sheet of formulae,
trade product: Desmodur L (TM),
or which may be obtained from diisocyanates by the
biuret reaction, see formula 2 of the sheet of formulae,
trade product: Desmodur N (TM),
2072332
or the polyisocyanates obtainable by the cyclization of
diisocyanates and having an isocyanurate basic structure, see
formula 3, trade product: Desmodur HL (registered trade mark),
formula 4: trade product: Desmodur IL (registered trade mark),
formula 5: trade product: Polurene KC (regis~ered trade mark),
formula 6: trade product: Polurene HR (registered trade mark),
formula 7: toluylene diisocyanate-isophorone diisocyanate
isocyanurate, or formula 8, trimeric isophorone diisocyanate
(isocyanurate T1890 of Chemische Werke HulS).
AS already mentioned above, the relevant compounds are
trade products which fre~uently do not have the above chemical
formulae in their pure form but are mixtures of certain
compounds of a similar structure. By average functionality is
meant that with regard to the isocyanate groups the trade
products have the given functionality of from 2.0 to 5,
preferably about 4.
me hydroxyl compounds used are anyhow at least a
monohydroxyl compound with an aliphatic and/or cycloaliphatic
hydrocarbon which may or may not be substituted with aryl
and/or halogen groups, or may contain one or more ether and/or
e~ter groups. Preferably, the monohydroxyl compound has a
molecwlar weight of at least 500 and more i~ particular of from
750 to 3500. An optimum dispersing activity i8 obt~ined with
these molecular weights. It is also ~q8~ibl~ to incor~orate one
or more substituents in the monohydroxyl CCmpOU~ ~hiCh
increases the compatibility with alkyd resins.
2072332
It may be important that in addition to the hydroxyl group
the relevant monohydroxyl compound has no substituents reactive
with isocyanates under the condition~ of preparation of the
dispersing agent according to the invention.
The monohydroxyl compounds used may be aliphatic,
cycloaliphatic and/or araliphatic compounds. Mixtures of such
compounds m~y also be used. Straight chained and branched
aliphatic or araliphatic compounds may be used. They may be
saturated or unsaturated. Saturated compounds are pre~erred.
The hydrogen atoms may be partly replaced by halogens,
preferably by fluorine and/or chlorine. When such substituted
compounds are used, they are preferably aliphatic monoalcoholæ.
Products are commercially available and the carbon atoms close
to the hydroxyl group, as is well known to those skilled in the
art, generally have no halogen atoms. Examples of specially
fluorinated alcohols include heptadecafluorodecanol or
C6F13CH2CH20H. The commercially available corresponding
products are frequently not uniform but mixtures of different
fluorinated compounds as obtained from technical synthesis.
The nohydroxyl compounds used may also be those which
contain at least one -0- and/or C00- group. They are therefore
polyethers, polyesters or mixed polyether-polyesters. Examples
of polyesters include those which may be obtained by the
polymerlzation of a lactone such as propiolactone,
valerolactone, caprolactone or substituted derivatives thereof,
using a monohydroxyl starting component. The starting
components used are monoalcohols, suitably with 4 to 30,
2072332
preferably 4 to 14 carbon atoms, such as n-butanol, relatively
long-chained, saturated and unsaturated alcohols such as
propargyl alcohol, oleyl alcohol, linoloyl alcohol, oxo
alcohols, cyclohexanol, phenyl ethanol, neopentyl alcohol, but
also fluorinated alcohols of the kind mentioned above. Alcohols
of the type described above and substituted and unsubstituted
alcohols may also be converted into polyoxyalkylene monoalkyl-,
aryl-, aralkyl- and cycloalkyl ethers by known methods of
alkoxylation with ethylene oxide and/or propylene oxide, and
these monohydroxypolyethers may be used in the manner
prescribed as starting components for lactone polymerisation.
Mixtures of the above-mentioned compounds may be used in all
cases. m ese polyesters suitably have a molecular weight within
the range of from about 300 to 8000, preferably 500 to 5000.
There may also be used monohydroxypolyethers obtained by
the alkoxylation of alkanols, cycloalkanols and phenols. These
polyethers suitably have a molecular weight within the range of
from about 350 to 1500.
Suitable dicarboxylic acid compounds may be obtained by
the reaction of a diol with a dicarboxylic acid or an
anhydride. It is possible to start fro~ a diol of higher
molecular weight such as a polyethylene glycol and to react it
with a single dicarboxylic acid or a dicarboxylic anhydride. It
is also possible to react a dicarboxylic acid of high molecular
weight with a diol of low molecular weight. Finally, it is also
pos~ible to react almost stoichiometric guantities of diol of
low molecular weight and dicarboxylic acid of low molecular
2072332
weight with each other under such conditions as to form as much
dicarboxylic acid as possible and anyhow no or substantially no
dihydroxy- or monohydroxy-monocarboxylic acid compound.
Preferred is the use of the reaction product of dicarboxylic
acid of low molecular weight with a diol of higher molecular
weight such as polyethylene glycol.
Preferably, the dicarboxylic acid compound used is a
hydrocarbon compound with at least eight carbon atoms contained
between the carboxylic acid groups. If desired, this carbon
chain may be interrupted by amlde, ether, ester, S, SO2 and/or
urethane groups. To improve the compatibility of the dispersing
agent with different materials, it is generally preferred that
the molecular weight of the dicarboxylic acid compound is at
least 500, more in particular of from 750 to 4000.
The ratio of the quantities of hydroxyl groups contained
in the monohydroxyl compound and the quantities of carboxylic
acid groups contained in the dicarboxylic acid compound may
vary within relatively broad limits, depending on their use.
Preferably, the dicarboxylic acid compound is present in a
deficiency with respect to the monohydroxyl compound. The ratio
of the number of hydroxyl groups originating from both types of
compounds varies from 1:2 to 5:1. Preferably, this ratio ranges
from 4:1 to 5:2.
An important component in the dispersing agent according
to the invention is a compound containing a basic ring
nitrogen. Suitable compounds are: N,N-diethyl-1,4-
butanediamine, 1-(2-aminoethyl)-piperazine, 2-(1-pyrrolidyl~-
2072332
ethylamine, 4-amino-2-methoxy-pyrimidine, 2-
dimethylaminoethanol, l-(2-hydroxyethyl)-piperazine, 4-(2-
hydroxyethyl~-morpholine, 2-mercaptopyrimidine, 2-
mercaptobenzimidazole. Particularly preferred are N,N-dimethyl-
1,3-propanediamine, 4-(2-aminoethyl)-pyridine, 2-amino-6-
methoxybenzothia~ole, 4-(aminoethyl)-pyridine, N,N-diallyl-
melamine, 3-amino-1,2,4-triazole, 1-(3-aminopropyl)-imidazole,
4-(2-hydroxyethyl)-pyridine, 1-(2-hydroxyethyl)-imidazole, 3-
mercapto-1,2,4-triazole.
Characteristic of these compounds is that per molecule
they contain at least one Zerewitinoff hydrogen atom, which
preferably reacts with the isocyanate groups, and that they in
addition contain a basic group which contains nitrogen and
which i8 not capable of forming urea with isocyanate groups.
These basic groups are also characterised according to the
state of the art by their pKa-value (compare US-A-3,817,944;
4,032,698 and 4,070,388). Compounds with basic groups having a
pKa-value of from 2 to 14 are preferred, especially those with
pXa-values of from 5 to 14 and most especially tho~e with pKa-
values of from 5 to 12. The pKa-value can be obtained from
tables. The limiting values given above refer to the
measurement of the pKa-value at 25C at an 0.01 molar
concentration in water. These basic groups also impart a
basicity to the addition compounds according to the invention,
as is also known in this field of the art (compare the above-
mentioned U.S. patent specifications). Due to these basic
groups, the addition compounds are capable of salt formation.
2~72332
Ll
According to the invention, they may also be used in the form
of such salts as dispersing agents.
Theæe salts are obtained from the resulting reaction
product by neutralisation with organic or inorganic acids or by
quaternisation. Salts with organic monocarboxylic acids are
preferred.
It is to be noted that it may also be possible to
incorporate a minor guantity of a dihydroxyl compound in the
dispersing agent according to the invention. The quantity
thereof is, however, always such that only a fraction, i.e.
less than 5%, preferably less than 2.5% of the isocyanate
groups is reacted therewith. Preferably, however, no dihydroxyl
compound is present.
The reaction of isocyanate groups takes place by applying
known methods. In general, it is preferred to carry out the
reaction in such a manner that in a first stage the
polyisocyanate is reacted with a mixture of a monohydroxyl
compound and a dicarboxylic acid compound. This reaction
generally occurs in a suitable solvent (e.g. hydrocarbons such
as xylenes, ethers such as dioxane, esters such as butyl
acetate, and dimethylformamide), in the presence of a catalyst
such as dibutyltin dilaurate, iron acetyl acetonate or
triethylenediamine. It is essential for the reaction to occur
under such conditions that at least one of the carboxylic acid
groups of the dicarboxylic acid reacts with the polyisocyanate.
This may be obtained by using a suitable catalyst.
2~72332
It is possible, but not preferred, to first react the
polyisocyanate with the monohydroxyl compound and to further
react the resulting reaction product with the dicarboxylic acid
compound.
After this reaction, in which in general about 40-80% of
the isocyanate groups will be reacted, the reaction is carried
out with a compound containing a basic ring nitrogen. This will
lead to a reaction of about 20-60~ of the isocyanate groups.
Isocyanate groups that may not have reacted are finally
deactivated by the reaction with a lower alcohol or a
comparable compound. Particularly butanol is suitably used.
The invention will now be illustrated by some examples but
is not limited to them.
r~nl~ A~ ~--r~--~r~
31.92 g caprolactone, 10.40 g HD-Ocenol 45/50 (Henkel &
Cie., D~sseldorf) are dispersed under an inert gas. 0.0012 g
dibutyltin dilaurate are added and heated to 170C with
stirring until a solid of 99% is obtained (about 8 h). The
product is solid at room temperature and slightly yellowish in
colour.
125.00 g polyethylene glycol having the average molecular
25 ma8S of 1000 are molten under an inert gas. 24.50 g maleic
anhydride and 16.61 g methoxypropyl acetate are added with
stirring and heated to 150C. The addition reaction is
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13
completely terminated as soon as an acid number of 93 mg KOHtg
iæ obtained; duration about 8 h. The resinous product is
yellowish-brown in colour and has a solid content of 90%.
ExamDle 1
24.21 g of a caprolactone polyester (Example A) and
63.00 g Desmodur IL~ (50% in butyl acetate) are dissolved in
31.29 g n-butyl acetate and 28.81 g methoxypropyl ace~ate under
an inert gas and with stirring. Then 10.63 g dicar~oxylic acid
(Example of Preparation B) and 0.02 tin octoate are added, and
the formulation is heated to 70C. After a reaction time of
2 h, 50% the NCO groups have reacted. One cools to 50C and
adds 3.36 g 3-amino-1,2,4-triazole dispersed in 19.05 g
N-methylpyrrolidone, and further stirs for 1 h. Then 6.75 g
n-butanol are added, and the temperature is maintained at 50C
for 2 h. The liquid end product is light yellow in colour and
nas a solid content of 35~.
Exa~le 2
36.32 g of a caprolactone polyester (Example A) and 63.00
g Desmodur IL~ (50% in butyl acetate) are dissolved in 46.94 g
n-butyl acetate and 43.22 g methoxypropyl acetate under an
inert gas and with stirring. Then 15.95 g dicarboxylic acid
(Example of Preparation B) and 0.03 tin octoate are added, and
the formulation is heated to 70C. After a reaction time of
2 h, 50% the NCO groups have reacted. one cools to 50C and
adds 6.49 g 2-amino-4-methylpyridine which are previously
2072332
14
dissolved in 25.~5 g N-methylpyrrolidone. The temperature is
maintained at 50c for another h, and 15.44 g n-butanol are
added. To complete the reaction, it is continued for another
2 h at 50C. m e end product is light brown in colour and has a
solid content of 35%.
Exa~Dle 3
48.43 g of a caprolactone polyester (Example A) and
8~.00 g Desmodur IL~ (50% in butyl acetate) are dissolved in
77.62 g n-butyl acetate and 44.94 g methoxypropyl acetate under
an inert gas and with stirring. Then 21.26 g dicarboxylic acid
(Example of Preparation B) and 0.04 tin octoate are added, and
the formulation is heated to 70C. After a reaction time of
2 h, 50% the NCO groups have reacted. One cools to 50C and
adds 10.02 g 1-(3-aminopropyl)-imidazole dissolved in 34.18 g
N-methylpyrrolidone. After 1 h, 17.09 g n-butanol are added,
and the temperature of 50C is maintained for another 2 h. The
end product is light yellow in colour and has a solid content
of 35%.
60.54 g of a caprolactone polyester (Example A) and 105.00
g Desmodur IL~ (50% in butyl acetate) are dissolved in 78.23 g
n-butyl acetate and 472.04 g methoxypropyl acetate under an
inert gas and with stirring. Then 26.57 g dicarboxylic acid
(Exdmple of Preparation B) and 0.05 tin octoate are added, and
the formulation is heated to 70C. After a reaction time of
2072332
2 h, 50~ the NCO groups have reacted. One c0018 to about 50C
and adds a solution consisting of 18.02 g 2-amino-6-
methoxybenzothiazole and 72.06 g N-methylpyrrolidone. After
1 h, 10.30 g n-butanol are added and maintained at 50C for
another 2 h. The liquid end product is light brown in colour
and has a solid content of 35%.
