Note: Descriptions are shown in the official language in which they were submitted.
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Antifoam based on oil-in-water emulsions
German Patent 2,157,033 discloses a process for
defoaming aqueous systems by means of emulsions which con-
tain C12-C22-alkanols and/or C12-C22-fatty acid esters
of dihydric or trihydric alcohols, as well as liquid paraf-
fin and/or C12-C22-fatty acids as antifoams and conven-
tional surfactants as emulsifiers. The emulsified water-
insoluble substances have a mean particle size of from 4
to 9 ~m. The known antifoam emulsions have the disadvan-
tage that they cream during storage and in some cases eventhicken to such an extent that such mixtures can then no
longer be pumped.
U.S. Patent 3,408,306 discloses a process for de-
foaming aqueous systems, in which the antifoam mixture
used cons;sts of from 80 to 97X by weight of a water-
soluble hydrophobic organic liquid (eg. a mineral oil,
long-chain alcohol, ester or amine) and from 3 to 20~ by
weight of finely divided solids (eg. silica, bentonite,
talc or titanium dioxide), which have been rendered hydro-
phobic. The antifoam mixture can, if required, containup to 5~ by weight of surfactant. An essential feature
of these antifoam mixtures is that the finely divided
solids are rendered hydrophobic with substances (eg. di-
methylpolysiloxane oils) which are usually used as anti-
foams. The preparation of finely divided solids which havebeen rendered hydrophob;c is technically complicated.
European Patent Appl;cat;on 149,812 discloses that
antifoams which are based on oil-in-water emulsions in
which the oil phase of the emulsion contains
(a) a C12-C26-alcohol, distillation residues which
are obtained in the preparation of higher alcohols by the
oxo synthesis or by the Ziegler method and which may or may
not be oxyalkylated, and/or
(b) a fatty acid ester of a C12-C22-carboxylic acid
with a monohydric, dihydric or trihydric C1-C18-alcohol
and, if required,
(c) a hydrocarbon having a boiling point above 200C
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or a fatty acid of 12 to 22 carbon atoms,
accounts for from 15 to 60% by weight of the emulsion and
has a mean particle size of from 0.5 to 15 ~0 can be stabi-
lized to prevent an increase in viscosity and creaming
during storage by adding from 0.05 to 0.5% by weight of a
high molecular weight, water-soluble homopolymer or copoly-
mer of acrylic acid, methacrylic acid, acrylamide or meth-
acrylamide.
It is an object of the present invention to make
the known antifoams more environmentally compatible, ie.
to reduce the chemical oxygen demand in wastewaters, while
substantially or completely maintaining the efficiency.
~ e have found that this object is achieved, accor-
ding to the invention, by antifoams based on oil-in-water
emulsions in which the oil phase of the emulsions contains
(a) a C1z-Cz6-alcohol, dist;llation residues which
are obta;nable in the preparation of higher alcohols by
the oxo synthesis or by the Ziegler method and which may
or may not be oxyalkylated, and/or
(b) a fatty acid ester of a C12-Cz2-carboxylic acid
with a monohydric, dihydric or trihydric C1-C18-alcohol
and, if required~
(c) a hydrocarbon having a boiling point above 200C
or a fatty acid of 12 to 22 carbon atoms,
accounts for from 5 to 50% by weight of the emulsion and
has a mean particle size of < 25 ~m, if the oil-in-water
emulsions contain finely divided, virtually water-insoluble,
inert solids whose surface has not been rendered hydro-
phobic.
Component (a) of the oil-in-water emulsions con-
sists in particular of natural or synthetic alcohols of
1Z to 26 carbon atoms or mixtures of alcohols. Examples
are myristyl alcohol, cetyl alcohol and stearyl alcohol.
The synthetic alcohols, which are obtainable, for examPle,
by the Ziegler method by oxidation of aluminum alkyls, are
saturated, straight-chain, unbranched alcohols. Synthetic alcohols
are also obtained by the oxo synthesis, this method
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generally giving mixtures of alcohols. Distillation resi-
dues which are obtained in the preparation of the above
alcohols by the oxo synthesis or by the Ziegler method may
also be used as component (a) of the oil phase of the anti-
foam emulsions. Other suitable components ta) of the saidoil phase are oxyalkylated distillation residues which can
be obtained by the above process for the preparation of
higher alcohols by oxo synthesis or by the Ziegler method.
The oxyalkylated distillation residues are obtained by
reacting the above distillation residues with ethylene
oxide or propyLene oxide or with a mixture of these. U~
to S ethylene oxide or propylene oxide groups undergo
addition per OH group of the alcohol in the distillation
residue. Preferably, 1 or 2 ethylene oxide groups are
added per OH group of the sa;d alcohol.
Fatty acid esters of C12-C22-carboxylic acids
w;th a monohydric, dihydric or trihydric C1-C1g-alcohol
are used as component (b) of the oil phase of the anti-
foam emulsion. The fatty acids on which the esters are
based are~ for example, lauric acid, myr;stic acid, palmi-
tic acid, stearic ac;d, arachic acid and behenic acid.
Palm;tates and stearates are preferably used. The stated
carboxylic ac;ds can be esterified using monohydric C1-C1~-
alcohols, eg. methanol, ethanol, propanol, butanol, hexa-
nol, decanol or stearyl alcohol, as well as dihydric alco-
hols, such as ethylene glycol, or trihydric alcohols, such
as glycerol. The ~olyhydric alcohols may be completely
or partially ester;f;ed. The oil phase of the antifoam
emulsions contains a compound of component (a) or (b) or
a mixture of components (a) and (b).
The components (a) and (b) can be used in any
ratio for the preparation of the antifoams. In practice,
for example, mixtures of (a) and (b) which contain from
40 to 60% by weight of (a) and from 60 to 40~ by weight of
(b) have proven useful.
The oil phase of the emulsion may additionaLly con-
tain a further class of water-insoluble compounds, which
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is referred to below as component (c). The compounds of
component (c) can account for up to 50~ by weight, based
on components (a) and (b), of the oil phase of the antifoam
emulsion. They may be added either to a mixture of com-
ponents (a) and (b) or to each of the compounds statedunder (a) or (b). Suitable components (c) are hydrocarbons
having a boiling point of more than 200C under 1013 mbar
and a pour point of less than 0C, and fatty acids of 12
to 22 carbon atoms. Preferred hydrocarbons are liquld
paraffins, such as the commercial paraffin mixtures, which
are also referred to as white oil.
The above compounds (a) and/or (b) and, if required,
(c) form the oil phase of the oil-in-water emulsions.
This phase accounts for from S to 50% by weight of the oil-
in-water emulsion, wh;le the aqueous phase accounts for
from 95 to 50~ by weight of the said emulsion, the percen-
tages in each case summing to 100. The mean particle size
of the oiL phase of the said emulsion is less than 25 ~m,
preferably from 0.5 to 15 ~m.
The essential feature of the present invention is
that the oil phase of the oil-in-water emulsions contains
finely divided, virtually water-insoluble inert solids
whose surface has not been rendered hydrophobic. The par-
ticle diameter of the said solids is less than 20 ~m, pre-
ferably from 0.1 to 10 um. The novel antifoams can also
be prepared by a method in which the finely d;vided, inert
solids are emuls;f;ed in a conventional oil-in-water anti-
foam, for example ;n an emuls;on of compounds (a) and/or
(b) and, ;f required, (c) in water. For the novel anti-
foams, it ;s poss;ble to use any ;nert solids which do notreact w;th the components of the antifoam mixture and fur-
thermore are virtually insoluble ;n water. Preferably
used inert solids are kaolin, chalk, calc;um sulfate,
barium sulfate, talc, microcrystalline cellulose and/or
crosslinked starch. Regarding the suitability of solids,
there are no restrictions apart from the fact that the
solids should be inert and should not have been rendered
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hydrophobic. 30th inorganic and organic solids which have
not been surface-treated can be used. Examples of suit-
able solids apart from those mentioned above are sheet
silicates, such as bentonite, montmorillonite, nontronite,
hectorite, saponite, volkonskoite, sauconite, beidellite,
allevardite, illite, halloysite, attapulgite and sepiolite,
and titanium dioxide, alumina, s;l;ca, satin white, syn
thetic aluminum silicates, crosslinked urea/formaldehyde,
melamine/formaldehyde and melamine/isobutyraldehyde conden-
sates and homopolymers and copolymers of styrene, whichare disclosed in, for example, ~ritish Patent 1,229,503.
Urea/formaldehyde condensates, which are also referred to
as methyleneureas, were obtained by condensing preconden-
sates of urea and formaldehyde in a molar ratio of 1 or
less than 1 in the presence of a strongly acidic catalyst
at a pH of less than 2 (cf. German Published Application
DAS 2,110,309) or by the process of U.S. Patent 3,931,063.
The condensates obtainable as described in German Laid-
Open Application DOS 2,547,966 are also suitable. Mixtures
of the inert inorganic solids, of the inert organic solids
or of the inert inorganic solids with the inert organic
solids may be used. The finely divided inorganic and
organic solids are used in a form which has not been ren-
dered hydrophobic and the~refore do not require any prior
coating or treatment with substances which impart hydro-
phobic propert;es.
The solids are preferably used ;n an amount such
that they replace from 5 to 30X of the oil phase of the
oil-in-water emulsions.
The novel antifoams are preferably prepared by a
method in which first the finely divided inert solids are
homogenized with the compounds (a) and/or (b) and, if
required, (c), and the resulting m;xture ;s thèn emulsi-
fied in water. The antifoams according to the invention
may also be prepared by emulsifying the finely divided
inert solids in a known oil-in-water antifoam, for example
in an emulsion of the compounds (a) and/or (b) and, if
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required, (c) in water. If the organic compounds which
form the oil phase are solid substances at room temperature,
they are first melted. One or more finely d;vided inert
solids are then introduced into the melt, thorough mixing
of the components being ensured. Components ~a) to (c)
can be m;xed with the inert solids at from 50 to 100C.
The result;ng mixture ;s then emulsified in water in order
to prepare the oil-in-water emulsion. This is done using
the conventional surfactants, which have an HLE value of
more than 6. These surfactants are oil-in-water emulsi-
fiers or typical wetting agents. Among the surfactants,
anionic, cationic or nonionic compounds may be used.
Anionic or nonionic surfdctants or mixtures of the two are
preferably employed. Examples of substances of the stated
type ar~ sodium salts or ammonium salts of higher fatty
acids, such as ammonium oleate or stearate, oxyalkylated
alkylphenols, such as nonylphenol or isooctylphenol, which
have been reacted with ethylene oxide in a molar ratio of
from 1:2 to 1:50, oxyethylated unsaturated oils, for
20 example the reaction products of 1 mole of castor oil and
from 30 to 40 moles of ethylene oxide, and the reaction
products of 1 mole of sperm oil alcohol with from 60 to
80 moles of ethylene oxide. Other preferably used emulsi-
f;ers are sulfonated oxyethylation products of nonylphenol
25 or octylphenol, wh;ch are ;n the form of the sodium or
ammonium salt of the corresponding sulfuric acid half-
ester. 100 parts by weight of the oil-in-water emulsions
usually contain from 0.5 to S parts by weight of an emulsi-
fiQr or an emulsifier mixture. A major part of the emulsi-
fier is dissolved in the aqueous phase. In addition tothe emulsifiers stated above, it is also possible to use
protective colloids, such as high molecular weight poly-
saccharides and soaps or other conventional additives,
such as stabilizers (reference may be made to European
Patent Application 149,812.
~---- ~The oil phase (a mixture of components (a)
to (c) and the inert solids) can be emuls;f;ed us;ng a
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conventional apparatus, for example a disperser. If the
oil phase is in the form of a solid material, it is first
melted and then emulsified in water. Emulsification of
the oil phase in water can be carried out at room temper3-
ture or elevated temperatures, for example at from 50 to
95C ~
Directly after the preparation, the antifoam emul-
sions have a viscosity of from 300 to 700 mPa.s. Surpris-
ingly, the oil-in-water emulsions suffer virtually no loss
of efficiency as antifoams as a result of adding the inert
solids, which in themselves are not effective as antifoams.
The particle size of the inert, water-insoluble solids is
always less than the particle size of the oil phase of the
oil-in-water emulsion and is no higher than 95~ of the
part;cle s;ze of the part;cular o;l-;n-water emwls;on
used.
The novel o;l-in-water emulsions are used as anti-
foams in foam-forming aqueous systems in an amount of
about O.OZ-0.5, preferably 0.05-0.3, part by weight of the
antifoam emulsion per 100 parts by weight of a foam-forming
med;um. The ant;foam emulsions according to the invention
are used in particular as antifoams in papermaking, and
are employed both in sulfite pulp cooking and in paper-
making, in the paper stock and in paper coating compounds.
The antifoams can also be used for controlling foam in
the food industry, in the starch industry and ;n waste-
water treatment plants.
In the Examples, parts and percentages are by
weight. The mean particle size of the particles of the
oil phase which are emulsified in water was determined
with the aid of a Coulter counter, the particle diameter
of the inert solids was from 0.5 to 15 ~m.
Determination of the foam value:
5 l of a foam-forming paper stock suspension are
circulated for 5 minutes in a channel made of transparent
plastic. The amount of foam formed on the surface of the
stock suspension is then measured in units of area (cm2)
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with the aid of a grid on the wall of the channel and is
stated as the foam value for assessing the efficiency of
an antifoam.
If the paper stock susPension is circulated in the
absence of an antifoam, the foam value after S minutes
is 1200 cm2. ~y adding, in each case, 2 mg/l of an effec-
tive antifoam to the paper stock suspension, this value is
substantially reduced, so that it constitutes a measure
of the efficiency of an antifoam. However, if instehd of
an antifoam 2 mg/l of an inert, finely divided (O.S-15 ~m)
solid which has not been rendered hydrophobic is aJded,
for example kaolin, CaS04, talc, chalk, barium sulfate,
crosslinked starch, TiO2, bentonite, Al203 or SiO2, the
foam value does not change.
EXAMPLE 1
20.5 parts of a mixture of glycerol triesters of
C16-C1g-fatty acids, a C16-C20-fatty alcohol mixture and
a mineral oil in a weight ratio of 14:10:6 are mixed with
10 parts of kaolin (mean particle diameter of more than
94% of the particles less than 1 ~m) at 70C in a stirred
container. This mixture is then emulsified in a sol-
ution of 2 parts of an emulsifier tadduct of 25 moles of
ethylene oxide with 1 mole of isooctylphenol whlch has
been reacted with sulfuric acid to give the sulfuric acid
half ester) in 67.5 parts of water. Advantageously, the
aqueous phase is initially taken in a dis~erser and the
kaolin-containing oil phase is added. The resulting oil-
in-water emulsion has a viscosity of 450 mPa.s at 20C
directly after the preparation and gives a foam value of
191 cm2 on testing the antifoam action. The mean par-
ticle size of the oil phase is 3 ~m.
COMPARATIVE EXAMPLE 1
30.5 parts of an oil phase consisting of glycerol
triesters of C16-C1g-fatty acids, a C16-C20-fatty alcohol
mixture and a mineral oil in a weight ratio of 14:10:6
are emulsifled at 70C in a disperser in 69.5 parts of an
aqueous phase comprising 67.5 parts of water and 2 parts
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of emulsifier (adduct of 25 moles of ethylene oxide ~ith
1 mole of isooctylphenol which has been reacted wieh sulf-
uric acid to give the sulfuric acid half ester). The
mean particle size of the oil phase is 3 ~m~ When the
efficiency as an antifoam is tested, a foam value of
189 cm2 is determined.
As shown by this Comparative Example, the content
of kaolin surprisingly produces virtually no reduction in
the efficiency of the antifoam according to Example 1.
~XAMPLE 2
15.5 parts of a mixture of glycerol triesters of
C16-Clg-fatty acids, a C16-Czo-fatty alcohol mixture and
a mineral oil in a weight ratio of 14:10:6 are mixed with
15 parts of kaolin (mean particle size of 94X of the
particles less than 1 ~m) at 70C and then emulsified
directly in 69.5 parts of a solution of 2 parts of the
emulsifier described in Example 1 in 67.5 parts of water.
The mean particle diameter of the oil phase of the oil-
in-water antifoam emul,ion is 2.5 ~m. On testing the
efficiency of the emulsion as an antifoam~ a foam value
of 182 cm2 is determined.
EXAMPLE 3
25.5 parts of a mixture of glycerol triesters of
C16-C1g-fatty acids, a C16-C20-fatty alcohol mixture and
a mineral oil in a weight ratio of 14:10:6 are heated to
70C and mixed w;th S parts of a finely divided chalk
(mean particle diameter of 96X of the particles less than
1 ~m). This Inixture is then emulsified in 69.5 parts of
an aqueous solution which contains 2 parts of the emulsi~
fier described in Example 1 dissolved in 67.5 parts of
water. The oil phase of the resulting oil-in-water emul-
sion has a mean particle size of 3.5 ~m. On testing the
efficiency as an antifoam, a foam value of 194 cm2 is
determined by the method of measurement described above.
EXAMPLE 4
15.5 parts of a mixture of glycerol triesters of
C16-C1g-fatty acids, a C16-C20-fatty alcohol mixture
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and 3 mineral oil in a weight ratio of 14:10:6 are heated
to 70C and mixed with 15 parts of chalk in which 96~ of
the particles have a mean particle size of less than 1 ~m.
This mixture is then emulsified directly in 69.5 parts of
S a solution of 2 parts of the emulsifier described in
Example 1 in 67.5 parts of water. The mean particle size
of the oil phase of the resulting oil-in-water emulsion
is 3.5 ~m. On testing the efficiency of this emulsion as
an antifoam by the method described above, a foam value of
187 cm2 is obtained.
EXAMPLE 5
15.5 parts of a mixture of glycerol triesters of
C16-C1g-fatty acids, a C16-C20-fatty alcohol mi~ture and
a mineral oil in a weight ratio of 14:10:6 are heated to
70C and mixed thoroughly with 15 ~arts of calcium sul-
fate having a mean particle size of 0.2 ~m. This mixture
is then emulsified in 69.5 parts of an aqueous solution
of 2 parts of the emulsifier described in Example 1. An
oil-in-water emulsion results whose oil phase has a mean
particle size of 3 ~m and which gives a foam value of
196 cm2 when tested as an antifoam by the method stated
above.
EXAMPLE 6
15.5 parts of a mixture of glycerol triesters of
C16-C1g-fatty acids, a C16-C1g-alcohol mixture and a
mineral oil in a weight ratio of 14:10:6 are heated to
80C and mixed thoroughly with 15 parts of talc having a
mean particle size of 0.5 ~m. This mixture is then emul-
sified in 69.5 parts of an aqueous solution of 2 parts of
the emulsifier described in Example 1. An oil-in-water
emulsion results whose oil phase has a mean particle size
of 3 um and which gives a foam value of 186 cm2 when
tested as an antifoam by the method stated above.
EXAMPLE 7
15.5 parts of a mixture of glycerol triesters of
C16-C1g-fatty acids, a C16-C20-fatty alcohol mixture
and a mineral oil in a weight ratio of 14:10:6 are heated
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~ O.Z. OOSO/38Z27
to 70C and mixed thoroughly with 15 parts of a microcrys-
talline cellulose having a mean particle size of less than
1 ~m. This mixture is then emulsified in 69.5 parts of an
aqueous solution which contains 2 parts of the emulsifier
S described in Example 1. An oil-in-water emulsion results
whose oil phase has a particle size of 4 ~m and which gives
a foam value of 200 cm2 on testing the efficiency as an
antifoam by the method described above.
EXAMPLE 8
15.5 parts of a mixture of glycerot triesters of
C16-C1g fatty acids, a C16-C20-fatty alcohol mixture and a
mineral oil in a weight ratio of 14:1G:6 are heated to 80C
and homogenized with 15 parts of a commercial crosslinked
starch whose mean particle size is less than 5 ~m. The
m;xture thus obtained is then emulsified in 69.5 parts of
an aqueous solution containing 2 parts by weight of the
emulsifier described in Example 1. The oil phase of the
resulting oil-in-water emulsion has a particle size of
8 ~m. On testing the efficiency as an antifoam, a foam0 value of 179 cm2 is determined for this emulsion.
EXAMPLE 9
3 parts of kaolin (particle diameter of 94% of the
particles < 1 ~m) are added, at 30C, to 100 parts of an
emulsion of 30 parts of a mixture of glycerol triesters
of C16-C1g-fatty acids, a C16-C20-fatty alcohol mixture
and a mineral oil in a weight ratio of 14:10:6 in 70 parts
of water which contains, in solution, 2 parts by weight of
the emulsifier described in Example 1. The mixture is homo-
genized in a disperser. The particle size of the oil phase
of the resulting emulsion is 6 um. In the test described
above, the emulsion g;ves a foam value of 184 cm2.
EXAMPLE 10
Example 9 is repeated, except that, instead of
3 parts, 12 parts of kaolin of the stated sPecification are
added in this case. An antifoam emulsion is obtained whose
oil phase has a particle size of 6 ~m and which gives a
foam value of 186 cm2 when tested by the above method.
