Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~` 60SI-156
53
The present invention relates to anti-foam silicone
compositions and more particularly the present invention re-
lates to improved anti-foam silicone compositions having
therein a silicone resin composed of monofunctional siloxy
units and tetrafunctional siloxy units.
As is well known, there are a number of processes in
various types of industries that result in a creation of
a foam during the process. Sometimes such a ~oam is desir-
able, in other cases the foam is undesirable.
Accordingly, in industries such as for example the
chemical industry, the food industry, the petroleum industry,
the textile finishing industry and the pharamaceutic in-
dustry in many cases during the processing of material undesir-
able foam is formed in some parts of the process. A foam is
formed when the rate of decay of foam is slower than the
creation of new foam bubbles. Accordingly, when you have
such a condition in a chemical or mechanical process there
results the creation of an ever increasing foam, that is so
stabilized that it does not decay very rapidly. Accordingly,
in such cases, it is desirable to utilize some means to
remove the undesirable foam. It is desirable to remove or
reduce the foaming in many processes, since the unwanted foam
may create a hazard, such as fire hazard or as is well re-
alized, the foam takes up a considerable amount of space
thus requiring more space to carry out the procèss in. It
may make the process itself difficult to operate efficiently.
Accordingly, in such processes in which undesirable foam is
formed, it is highly desirable to have some means of re-
ducing or completely removing the foam. Although there are
3Q many ways cf defoaming a process, the most desirable is the
chemical means since thïs usually is the most efficient way
to remove the foam. Thus, as is well known in industry by
. -
` 60SI-156
111~4453
the addition of a small amount of an anti-foaming agent to
a foamed composition, there results a rapid break-up of the
foam.
Accordingly, as is well-known, one type of such anti-
foaming agents that are widely used are silicone anti-
foaming agents. Examples of silicone anti-foaming com- -
positions are for instance to be found in U.S.Patent No.
2,894,913 dated July 14, 1959, U.S. patent No. 3,423,340
dated July 21, 1969, U.S. patent 3,076,768 dated February
5, 1963 and U.S. patent No.3,856,701 dated December 24, 1974
as well as in Chemistry and Technology of Silicones - Walter
Noll - Academic Press, N.Y. (1968), Pages 626-627 and
Encyclopedia of Polymers, Science & Technology - John Wiley
& Sons, Inc. (1967), Volume II, Pages 164 - 170 and Volume
12, page 557. While most of the above art deals with some
aspect of non-silicone and silicone anti-foam compositions,
such art does not disclose improvements that can be made on
the prior art silicone antifoam compositions. Dimethyl-
polysiloxane polymers are widely known in the silicone
industry. While such dimethylpolysiloxane polymers have very
many well known uses, it is also well known they can be
; utilized as anti-foam agents. It has been found that the
anti-foaming capabilities of such dimethylpolysiloxane polymers
can be improved by incorporating into the composition a
certain amount of a silica filler, such as fumed silica or
precipitated silica. In addition, it has been found that
the anti-foaming properties of dimethylsiloxanes could also
be improved by preparing and using such dimethylpolysiloxanes
without or with a silica filler in the form of an emulsion.
Usually such emulsions comprise the dimethylpolysiloxane
polymer, a silica filler, water and emulsifying agent where-
in the ingredients are sùbjected to high shear agitation
: '
-- 2 --
60SI-156
and colloidal mill shearing to produce a stable emulsion.
The advantage of using such a mixture and specifically a
silicone anti-foaming agent such as described above and
specifically one in which the main ingredient is the dim-
ethylpolysiloxane, is the dimethylpolysiloxanes are simple
and efficient to produce in silicone industry and also at
the same time are very effective as deforming agents.
Accordingly, prior workers in the art have strived to
improve the defoaming efficiency of dimethylpolysiloxanes
utilized in anti-foam compositions. As it has been stated
one successful attempt at this has been to incorporate a
fumed or precipitated silica in with the dimethylpolysiloxane
polymer to form the silicone anti-foam composition. As a
further improvement, it has been found that when silazane
treated precipitated siliea is incorporated into a dim-
ethylpolysiloxane there results in an improved anti-foam
eomposition. For instance note the disclosures of Releigh
U.S. patent No. 4,005,044 dated January 25, 1977, and U.S.
patent No. 4,012,334 dated Mareh 15, 1977. r~he above
Raleigh and Raleigh, et al patents disclose not only that
precipitated sili`ca treated with a silazane ean be in-
eorporated in dimethylpolysiloxanes to result in an improved
silicone anti-foaming composition but such disclosures
also set forth that by use of precipitated silica treated
with silazanes the silica filler can be more easily dis-
persed into the dimethylpolysiloxane to result in the
improved compositions of the above patents. However, irres-
pective of the ease or diffieulty of incorporating the
fillers into the dimethylpolysiloxane, it is still desirable
to improve the anti-foam effieieney of dimethylpolysiloxanes
even further, so that less amounts of the silieone anti-foam
eomposition ean be utilized to destablize a partieular foam.
- 3 -
- , .
` 60SI-156
1~14~S3
It should be noted the silicone resins are also well known.
One preferred type of silicone resin for many application
is a silicone resin composed of monofunctional siloxy units
and tetrafunctional siloxy units. Silicone resins are well-
known additives so as to stabilize foams which are desirably
produced and cured as such from well-known plastic systems.
For instance, note that the disclosure in Simoneau, U.S.
Patent ~o. 3,730,931 dated May 1, 1973 which discloses the
utilization of silicone resins composed of monofunctional
units and tetrafunctional siloxy units as the stabilizing
additive and surfactant in the formation of polyvinyl
chloride cured foams. Accordingly, it was unexpected that
the utilization of a silicone resin composed of monofunctional
and tetrafunctional siloxy units in combination with a dim-
ethylpolysiloxane would enhance the anti-foaming properties
of such dimethylpolysiloxanes or diorganopolysiloxanes.
Accordingly, it is one object of the present invention
to provide for an efficient silicone anti-foam composition.
It is an additional object of the present invention
to provide for an efficient silicone anti-foam composition
by means of incorporating into a diorganopolysiloxane polymer
a silicone resin composed of monofunctional and tetra-
functional siloxy units so as to enhance the anti-foam
properties of the diorganopolysiloxane polymer.
It is yet an additional object of the present invention
to provide for a very efficient antî-foam silicone com-
position by incorporating in a diorganopolysiloxane polymer
a silicone resin in combination with a silica filler.
It is still an additional object of the present in-
vention to provide a process for forming an improved anti-
foam silicone composition having as its basic ingredient a
diorganopolysiloxane polymer.
- 4 -
~ 60SI-156
It is yet a further object of the present invention to
de~oa~ln~
provide a process for efficiently ~cfor~ing a foam by adding
to such foam a small quantity of a composition which is a
mixture of a diorganopolysiloxine polymer, a silica filler
and a silicone resin. These and other objects of the
present invention are accomplished by means of the disclosure
set forth herein below.
In accordance with the above objects of the present
invention there is provided by the present invention a
silicone anti-foam composition comprising a diorganopolysiloxane
polymer having a viscosity varying from 100 to 100,000 centi-
poise at 25C with the organo groups being selected from the
class consisting of monovalent hydrocarbon radicals and
halogenated monovalent hydrocarbon radicals and from 1 to
15~ by weight of said diorganopolysiloxane of a silicone resin
composed of R3Sioo 5 units and SiO2 units with the ratio of
the monofunctional units to the tetrafunctional units varying
from .25 to .75. Such a silicone resin can contain anywhere
from .1 to 6% of hydroxyl group and preferably contains from
2 to 6% hydroxyl groups. -
In the preferred embodiment of the present invention
there is present in such anti-foam composition from .5 to
15% by weight of a filler selected from the class consisting
of fumed silica and precipitated silica, which may be treated
or untreated. Most preferably, the filler is precipitated
silica which is desirably treated with cyclic polysiloxanes,
low molecular weight linear polysiloxanes or more preferably
treated with silazanes, such as hexamethyldisilazane. It
co~p~Sl~ons ~onf~ln~ng
has been found that such silicone anti-foam ~mpoci-tion cont~ins
a diorganopolysiloxane polymer, a silicone resin composed of
c~nd
monofunctional and tetrafunctional siloxy units ~ a precip-
itated silica filler which is preferably treated with silazanes
~ 5 ~
60SI-156
1~44S3
results in the most efficient anti-foam composition. In
order to impart to such silicone anti-foam compositions, the
improved dispersability in aqueous systems it is desirable
to form an emulsion from the above ingredients in water utiliz-
ing as emulsifying agents such well known emulsifying agents
as sorbitan monostearate, polyoxyethylene sorbitan monos-
A tearate and/or polyoxyethylene stearate. The use of thesilicone anti-foam composition in the form of a water emulsion
results in the maximum efficiency in dispersing the silicone
composition in foamed aqueous systems. Accordingly, the
silicone anti-foam composition that is preferably produced and
utilized in aqueous systems is in the form of an emulsion.
It should be noted that the composition is effective
not only in defoaming aqueous systems, but it is also
effective in defoaming some organic systems other than aromatic
organic systems.
As it has been stated previously, although the silicone
resin of the instant case may be utilized with a very low
silanol content, it is preferred that the silanol content
of the resin vary from 2 to 6~. It has been found that the
higher the silanol content of the silicone resin composed
of monofunctional and tetrafunctional siloxy units is,
the better ~ its efficiency in defoaming a foamed system.
In addition, it is desirable to utilize in a silicone anti-
; foam composition a silica filler having 1 to 15~ by weight
of hydroxyl groups, which is treated with a silazane.
However, it should be noted that the instant anti-foam
compositions are effective even with an untreated precipitated
silica fiIler or even with a fumed silica filler at a con-
centration of .5 to 15% by weight of the diorganopolysiloxane.
The preferred anti-foam compositions of the instant case
can be prepared by simply mixing the diorganopolysiloxane
- 6 -
.
~ 60SI-156
~1~4~S3
polymer and the silicone resin with treated or untreated
silica filler with high shear agitation or the mixing can
be advantageously carried out at elevated temperatures as
will be disclosed herein below.
The diorganopolysiloxane polymer, which is the base
anti-foam ingredient in the composition of the instant
case can be any diorganopolysiloxane polymer having a
viscosity varying from 100 to 100, 000 centipoise at 25 and
more preferably having a viscosity varying from 100 to 2,000
centipoise at 25C. The organo groups can be any organo
group commonly associated with such polymers and can generally
be selected from alkyl radicals of 1 to 8 carbon atoms such as
methyl, ethyl, propyl; cycloalkyl radicals such as cyclohexyl,
cycloheptyl, cyclooctyl; mononuclear aryl radicals such as
phenyl, methylphenyl, ethylphenyl and alkenyl radicals such
as vinyl, allyl, etc. and also haloalkyl radicals such as
3,3,3 trifluoropropyl, etc. Most preferably the organo
groups in such diorganopolysiloxane polymers are selected - -
from lower alkyl radicals of 1 to 8 carbon atoms and are
most preferably methyl. Such polymers have preferably up to
.1% by weight of hydroxyl groups in them. It is preferred
the diorganopolysiloxane polymer have some hydroxyl groups
in the polymer since it has been found that this amount of
silanol enhances the anti-foam ability of the diorgano-
polysiloxane polymer. In addition, the diorganopoly-
siloxane polymer may have up to 10% by weight of tri-
functional siloxy units. As a more specific embodiment,
the diorganopolysiloxane polymer may be selcted from
polymers having the formula R'SiO4 a where R' is selected
from monovalent hydrocar~on radicals and halogenated radicals
as explained previously and where a varies from 1.9 to 2.1.
- 7 -
60SI-156
S~3
Such polymers are very well known in the silicone art and
can be produced by various well known methods. One such
method is to hydrolyze diorganodichlorosilanes in water and
purify the hydrolyzate product by preferentially distilling
out cyclic polysiloxanes to leave behind the low molecular weight
diorganopolysiloxane polymer that is formed. Such a procedure
is utilized to produce diorganopolysiloxane polymers in the
~iscosity range of 100 to 500 centipoise at 25 C. For the
higher molecular weight polymers a different procedure is
utilized. In such a procedure tetraorganocyclipolysiloxanes
are taken and equilibrated at elevated temperatures, that is
temperatures above 100C in the presence of acidic catalysts
S6~J~oJ7~:
such as toluene ~olon-i~ acid with the proper amount of chain
stoppers. Such chain stoppers are most commonly hexamethyl-
disiloxane, octamethyltrisiloxane, etc. The amount of chain
stoppers in the reaction mixture will determine the final
viscosity and molecular weight of the polymer that is formed
by such equilibration procedure. Such a procedure is com-
monly utilized to produce diorganopolysiloxane polymers and
more preferably dimethylpolysiloxane polymers of a vis-
cosity of anywhere from 500 to 10~,000 centipoise at 25C.
After the equilibration reaction has been completed, the
acid catalyst is neutralized with a mill base and the un-
reacted cyclics are stripped off.
In the present anti-foam silicone composition of the
instant case, there is preferably present a silicone resing
at a concentration of generally anywhere from l to 15% by
weight of the dior~anopolysiloxane polymer and more pre-
ferably at a concentration varying anywhere from 5 to 12% by
weight of said diorganopolysiloxane polymer. Such a silicone
resin, as stated pre~iously, is composed of R3SiOo 5 units and
SiO2 units where the ratio of the monofunctional units and
- 8 -
~ 60SI-156
53
tetrafunctional units varies from .25 to .75. Such a resin
may be a condensed resin in which most of the silanol groups
are condensed out or it can be an uncondensed silicone resin ~ -
where most or all of the silanol groups in the silicone
resin are uncondensed. Generally, the silicone resin in the
antifoam silicone compositions of the instant case, contains
anywhere from .1 to 6% by weight of hydroxyl groups and pre-
ferably contains from 2 to 6~ by weight of hydroxyl groups
for maximum anti-foam properties. The procedure for making
such a silicone resin, is also well known as disclosed in the
foregoing Simoneau, et al U.S. Patent No. 3,730,931 dated
May 1, 1973. Accordingly, such a silicone resin may be
produced by hydrolyzing in water a diorganodichlorosilane
and a tetrachlorosilane in the appropriate amounts to obtain
the desired ratio of monofunctional units to tetrafunctional
units in the silicone resin product. The silicone resin
hydrolyzate that is formed is then seprated from the excess
water and acid and purified by well known techniques, such as
for instancej by the addition of water and washing the silicone
resin hydrolyzate to remove excess acid until the acid content
is below 10 parts per million. In a similar procedure, such
a resin can be formed by for instance hydrolyzing a trior-
ganochlorosilane and ethylorthosilicate in ether. In addition,
the hydrolysis can be carried out in hydrolysis medium com-
posed of water and a water-immiscible organic solvent where
the silicone resin hydrolyzate is soluble in the water-
immiscible organic solvent and thus can be extracted from
the water and thus purif;ed by well known refluxing pro-
cedures. Such solvents are for instance xylene, toluene,
benzene, etc. If it i5 desired to concentrate the silanol
groups in such a silicone resin hydrolyzate that is formed
then there may be simply added to a solution of the silicone
~ .
~ 60SI-156
S:~ ,
resin in water-immiscible solvent anywhere from 10 parts to
500 parts per million of KOH and the mixture can be heated
at elevated temperatures of above 100C for a period of time
varying from l to 8 hours so as to reduce the silanol content
to below .5% by weight. However, as mentioned previously,
it is not desirable that the silicone resin that is utilized
in the compositions of the instant case to have a low silanol
content. For maximum anti-foaming imparting properties, it
is desired that the silicone resin have a silanol content of
anywhere from 2 to 6% by weight. In such anti-foam composition,
the third necessary ingredient is a filler. Generally, there
may be present anywhere from .5 to 15% by weight of a silica
filler by weight of the diorganopolysiloxane polymer. More
preferably, the filler is utilized at a concentration of any-
where fxom 5 to 15% by weight, based on the weight of the
diorganopolysiloxane polymer in the composition of the instant
case. Such a filler can be any precipitated or fumed silica
filler and desirably has a hydroxyl content of anywhere from
1 to 15~ by weight. Preferred precipitated silica fillers
thay may be utilized that are commercially available for
example from the Philadelphia Quartz Company sold under the
name of QUSO-F ~, S.C.M. Glidden Durkee Company sold as
Silcron G-lQ~, J.M. Huber Corporation sold as Zeothex 95~ and
W.R. Grace Company sold as Syloid-26~. All these precipitated
silica fillers are generally indentified as hydrate silicon
dioxide having a surface axea from about 300 to 400 meters
per gram and preferably having a moisture content generally
in the area of 1 to 15~ by weight and more preferably having
a moisture content of about 7 to 15% by weight. Although it
is desirable to utilize the precipitated fillers of the
high hydroxyl content, fumed silica in the above concentration
may be utilized in the instant invention. If fumed silica
-- 10 --
~4~jj3 60-SI-l56
is utilized it is preferred that it have a hydroxyl content
in the above ranges. However, fumed silica with a hydroxyl
content, that is lower than desired will still act as an anti-
foam additive in the composition although not as effective
as precipitated silica. The silica filler functions in the
anti-foam silicone composition to first impart some anti- -
foaming properties to the composition; second to enhance the
dispersability of the silicone anti-foam composition in the
foamed system; and thirdly, to enhance the stability of any
emulsion that might be formed from the silicone anti-foam
composition of the instant case as will be explained below.
Accordingly, for maximum effectiveness precipitated or
fumed silica having a silanol content in the area of 7 to
10~ or higher is preferred in the instant invention. However,
fillers below this level will also function effectively
although to a lesser extent. The filler may be treated with
filler treating compound since this results in the filler
enhancing the dispersability properties of the silicone
antifoam composition and in a more stable emulsion when the
silicone anti-foam composition is emulsified. Examples of
suitable treating agents for the fillers utilized in the anti-
foam silicone compositions of the instant case are for in-
stance silazanes, low molecular weight linear polysiloxanes
any cyclic polysiloxanes, such as octamethylcyclotetrasiloxane.
An example of a suitable silazane is hexamethyldisilazane.
The silicone anti-foam composition of the instant case
can simply be formed from the diorganopolysiloxane polymer
within the abo~e description containing therein the desired
amount of the silicone resin composed of monofunctional and
tetrafunctional siloxy units. There should be noted in this
respect that there is another type of resin similar, to the
above that may be utilized in the practice of the instant case.
~ 3 6OSI-156
Such a silicone resin may be composed of monofunctional siloxy
units, difunctional siloxy units and tetrafunctional siloxy
units.
Accordingly, such a silicone resin may be composed of
R'' SiO monofunctional units SiO tetrafunctional units and
3 0.5 2
R''2Sio difunctional units with the ratio of monofunctional
units to tetrafunctional units, to a difunctional units being
from .25 - .75 to 1 to .05 - .1 with the foregoing .1 to 6%
by weight of silanol groups. Such a silicone resin is formed
much in the same way as a silicone resin composed of only
monofunctional siloxy units and tetrafunctional siloxy units.
Both R' and R'' in the foregoing resins can be selected from
any of the monovalent hydrocarbon radicals and halogenated
monovalent hydrocarbon radicals identified above and recited
for the organo groups of the diorganopolysiloxane polymer.
Most preferably, R' and R'' are selected from alkyl radicals
of 1 to 8 carbon atoms vinyl and phenyl radicals. Most
preferably, R' and R;; are selected from methyl and vinyl.
Such a silicone resin as stated previously, can be produced
by the same method as was utilized to produce the silicone
resin composed of monofunctional and tetrafunctional siloxy
units except there is utilized as an additional reactant a
difunctional organo silane, as for instance diorganodichloro-
silane where the organo groups are as identified above for
R''. More information as to the preparation of such resins
can be found in the foregoing Simoneau et al U.S. Patent No.
3,730,331 dated May 1, 1973.
As stated previously, the instant anti-foam composition
can specifically consist of only the diorganopolysiloxane
polymer most commonly a dimethylpolysiloxane in combination
with the silicone resin composed of monofunctional and tetra-
; - 12 -
~ 3 60SI-156
functional siloxy units. In a simple procudure such a mixture
is prepared by simply dissolving the silicone resin in a solvent
and adding the solution to the diorganopolysiloxane polymer
and then with constant agitation, then the mixture is heated
to remove all the solvent from the composition. As constituted,
such a composition can be utilized as an antifoam silicone
composition with improved results to de~oam foamed systems.
In addition, the anti-foam composition in the instant
case can also include the sillca filler as explained above.
Accordingly, such anti-foam composition would comprise the
diorganopolysiloxane polymer, the silicone resin composed of
monofunctional and tetrafunctional siloxy units and a silica
filler. The procedure for preparing such a composition com-
prises mixing the diorganopolysiloxane polymer and the filler
and from 1 to 2~ by weight of the diorganopolysiloxane polymer
of oleic acid. The oleic acid is simply used in this pro-
cedure to help wet out the silica filler and prevent it from
clumping up while it is dispersed in the diorganopolysiloxane
polymer which has also incorporated the silicone resin in it.
Thus, after the mixture of the silicone resin and the dior-
ganopolysiloxane polymer is formed there is simply added to
such a mixture the amount of the desired silica filler with
the desired silanol content and the 1 to 2~ of oleic acid to
facilitate the dispersion of the filler. This is carried
out with high shear agitation. It is preferably desired
at that point after some agitation under high shear to raise
the temperature of the mixtures to 100 - 200 C for 1 - 3 hours
so as to vent off volatiles, and to facilitate the dispresion
of the filler in the silicone fluid. The resulting mixture
may be passed through a homogenizer to reduce the particle
size of the silica filler dispersed in the silicone fluid
and aid in the dispresion of the filler in the fluid. The
'
- 13 -
.
60SI-156
11e~4~3
agitation is then continued for another 1 - 9 hours at a tem-
perature above 150C and in the range of 100 - 200 C.
Accordingly, after such mixing of the filler into the silicone
fluid with high shear agitation for a period of time varying
anywhere from 2 to 6 hours at elevated temperatures of 100 -
200 C and more preferably at 150 - 200C the mixture is cooled
to room temperature under agitation and can be utilized as
such as a silicone anti-foam composition, in accordance with
the disclosure of the instant case. Various techniques may
be utilized to aid the dispersion of the filler in the silicone
compositions so as to form a stable dispersion of the filler
in the silicone fluid.
It is also possible to urilize a more sophisticated form
of the silicone anti-foam composition of the instant case by
preparing it in the form of an emulsion and specifically an
oil in water emulsion. The desirability of this is that
with the use of such emulsions, the anti-foam silicone compo-
sitions of the instant case is easily dispersed in aqueous
foam systems and accordingly, is more efficient and more
effective in smaller quantities in deforming the aqueous foam
system and at a faster rate than is the case when such
emulsions are not utilized.
As emulsifying agents, there can be utilized any emulsify-
ing agents which are acceptable in the foamed system to which
the anti-foam silicone composition will be added to. As --
emulsifying agents are compounds selected from conventional
emulsifiers for example such as polyoxyethylene sorbitan
f~ monostearate (Tween 6~) sorbitan monostearate (SPAN 6~),
polyoxyethylene stearate (Myrj 52~), and mixtures thereof.
3a For most food contact application, it is preferred to utilize
as emulsifying agents a mixture of sorbitan monostearate
(Span 60), polyoxyethylene stearate (Myrj 52S), commercially
- 14 -
11~4~3 60SI-156
available from the Atlas Chemical Company. Of course, as is
well known, other tradition~l or desired ingredients may be
added to emulsify anti-foam compositions of the instant case.
For instance sorbic acid can be added at a concentration of
anywhere from .01 to .1% by weight of the composition as a
bactericide. In forming such an emulsion, and as disclosed
in the Raleigh 4,005,044 preferably the emulsifying agent is
dissolved in water, the diorganopolysiloxane with the silicone
resin is dispersed in the emulsifying agents water solution;
then a silazane treated silica filler is mixed into the dis-
persion and the resulting composition is milled. Although
such a procedure is preferred since it speeds the dispersion
of the filler to quickly form a stable emulsion, the present
invention is not limited solely to such a mixing procedure.
The method of Raleigh U.S. patent No. 4,005,044 dated
January 25, 1977, is simply indicated above as the preferred
method of producing the emulsion. Other procedures of forming
the emulsion of the instant invention utilizing the anti-
foam ingredients of the instant case, can be utilized to
prepare the emulsion compound. One general method for producing
the emulsion compound of the instant case and which is dis-
closed as exemplary in the Examples below consists of adding
emulsifying agents such as sorbitan monostearate and oxyethy-
lene stearate to water and heating the resulting mixture to
temperatures at 60 - 100C under high shear agitation. To
this mixture there may be added the desired amount of the anti-
foam composition consisting of the anti-foam compound which
was described and was prepared as was discussed previously,
that is the incorporation of the silica filler with high
shear agitation into the fluid composed of the silicone resin
and the diorganopolysiloxane polymer.
~ccordingly, after the anti-foam compound has been added
- 15 -
60SI-156
4~53
at a temperature between 60 and 100C mixing is continued
for a period of time of anywhere from 1 to 5 hours until
the mixture is uniform. Then additional water may be
added to dilute the emulsion to the desired degree while
still heating at a temperature of 60 - 100C while at the same
time maintaining the high shear agitation. The composition
may then be cooled somewhat so that it can be handled on a
colloidal mill and processed in the colloidal mill for a
period of time of anywhere from 1 to 4 hours until the
emulsion is uniform. The mixture that results is then a stable
emulsion and may be utilized as an anti-foam composition with
good dispersability. This procedure which was utilized in
the Examples is given as exemplary only. It should be noted
that irrespective of which procedure is utilized the procedure
should be adopted to fit the particular needs of the specific
application. Any method for mixing the ingredients can be
utilized which procedures a suffic ently stable emulsion in
a short period of time.
It should be noted in this respect and with the respect
to the emulsion compound that is formed that is the emulsion
is too stable then there will be difficulty in utilizing it
since it will tend not to disperse efficiently as an anti-
foam in the foamed system to which it is applied. If the
emulsion is too unstable, on the other hand then the emulsion
has a short shelf stability. It is preferred that the
emulsions prepared in accordance with the instant case have
a shelf stability of 6 months to a year. The Examples below
are given for the purpose of illustrating the invention of the
instant case. They are not being given for any purpose of
setting limitations on the instant invention. All parts
are by weight. In the compositions and compounds that were
tested in the Examples, three test procedures were utilized
- 16 -
60SI-156
to evaluate the compound. Thus, the compounds were evaluated
for their viscosity after the particular composition was
formed, then in the case of emulsions the sedimentation
volume was determined. This procedure involves taking 40 cc's
of the emulsion and spinning it at 3000 rpm's in a centri-
fuge with a six inch arm for 30 minutes then checking the re-
distribution of the emulsion to note how much oil has separated
out at the top of the sample and how much sediment has been
formed at the bottom of the sample in cc's. This test is
simply for testing the stability of the emulsion that has been
formed. The most important test that has been run in the
examples was the test to determine the defoaming effectiveness
of the emulsion that was formed. Such a test, which procedure
will be recited below has been developed by the Silicone
Products Department of the General Electric Company for
testing its anti-foam compounds. This procedure which was
utilized to obtain the anti-foam value of the compounds and
fluids recited in the examples below in milligrams of anti-
foam additive per milliliter of a soap solution is as
follows:
(.05% solution of sodium lauryl sulfate)
The equipment utilized was a two beater kitchen mixer;
a 1500 milliliter breaker; a 4 dram vial with dropper; an
analytical balance, a 50 milliliter burette graduated to
a .1 milliliter; and .5% solution of sodium lauryl sulfate.
The time and sequence for the successive additions of reagent
to a sample which are described in the procedure are to be
duplicated as closely as possible. The elapse time between
the successive additions of sodium lauryl sulfate solution
is to be no greater than 30 seconds. In the procedure there
is used in sequence toluene, acetone and distilled water to
rinse the breaker and beaters between tests. A test tem-
6osI-l56
perature cf 25 C is preferred. Whatever temperature is
utilized in the test should be recorded.
The procedure comprises:
l. to a 1500 milliliter breaker which has been arranged
for mixing with the mixed, there is added 200 milliliters of
distilled water. The mixer which is equipped with two
beaters only is utilized at its maximum speed.
2. Add at a maximum rate of the .5% by weight of the
sodium lauryl sulfate solution until the foam height just
covers the beaters.
3. Immediately add enough sample to collapse the foam,
usually one to two drops would suffice during preconditioning.
4. After the foam level has subsided again, add at a
maximum rate of .5~ by weight of sodium lauryl sulfate as
described in Step 2.
5. Again there is added sufficient anti-foam compound
to break the foam.
6. After the foam level has subsided, shut the mixer
off. The time interval between the following two steps
should be no longer than lO minutes.
7. Weigh the bottle containing approximately lO grams o~
sample and a medicine dropper graduated to + .001 grams.
Record the weight as Wl.
8. Turn the mixer to maximum speed, record the volume
of sodium lauryl sulfate reagent in the burette. Repeat
Step 2 (each time noting the volume of reagent used) and
Step 3 until 5 successive additions of reagent and sample
have been made.
9. Weight the weighing bottle with sample and dropper.
Record the weight as W2.
10. Total the volume of each of the 5 additions of
sodium lauryl sulfate added in Step 8. Record the volume
- 18 -
,
~ 4S3 60SI~156
as Vt Divide by 5 to obtain the average volume Va. Divide the
average by 4. Add and subtract this result to Va to give
the range Vt - Vu. Compare each of the 5 individual volumes
to this range. They must fall within the range or else the
test is to be repeated.
11. Calculate the ratio R3 of the total weight in
milligrams sample used to total in milliliters of sodium
lauryl sulfate used; Calculating R3 in accordance with the
formula, the formula being R is = Wl -W2
10 Vt
12. Finally convert milligrams of sample versus milli-
liter of sodium lauryl sulfate solution to milligrams of
silicone per milliliter of sodium lauryl sulfate solution
so as to arrive at the anti-foam value of the sample utilizing
the appropriate conversion factors, which anti-foam values
are set forth in the Examples below. Utilizing this procedure
there is determined how many milligrams of the silicone
composition is needed to defoam the particular foaming agent.
Sodium lauryl sulfate reagent is an excellent foaming agent.
Accordingly, using this procedure for determining the
anti-foam value of the silicone compound or emulsion, as
well as the test for determining the stability of the emulsion,
the following examples were carried out: - All of the parts
in the examples are by weight.
EXAMPLE I
The following compounds and fluids were prepared for
testing as will be explained below.
Compound A - comprising a 100 centipoise at 25 C
of a dimethylpolysiloxane polymer.
Compound B - comprising a 350 centipoise at 25 C of
a dimethylpolysiloxane polymer.
- 19 -
~ 4~53 60SI-156
Compound C - comprising dimethylpolysiloxane polymer
having a viscosity of lQ0 centipoise at 25C
Compound D - comprising 95% by weight of a dimethyl-
polysiloxane of a viscosity of 350 centipoise
at 25C plus 5% by weight of a silicone resin
composed of trimethyl siloxy units and SiO2
units with a ratio of the monofunctional to
tetrafunctional units is 0.65-0.70 and with
the hydroxyl content is .28~.
Compound E - comprising 95% by weight of a dimethyl-
polysiloxane polymer having a viscosity of
350 centipoise at 25C plus 5% by weight of
a silicone resin composed of trimethyl siloxy
monofunctional units and SiO~ tetrafunctional
siloxy units with a ratio of the mono-
functional to the tetrafunctional siloxy units
is 0~65 - 0.70 and which has a silanol content
of 2~ by weight.
Compound F - comprising 90% by weight of a dimethyl- :
polysiloxane polymer of a viscosity of 350
centipoise at 25C plus 10% by weight composed
of a condensed silicone resin having trimethyl
siloxy monofunctional units and SiO2 tetra-
functional units with the ratio of the mono-
functional to tetrafunctional units is O.Ç5
- 0.7 and where the silanol content is .2~%.
Compound G - comprising 90% by weight of a dimethyl-
polysiloxane polymer of a viscosity of 350
centipoise at 25C plus 10~ of a silicone
Lesin composed of trimethyl siloxy mono-
functional units and SiO2 tetrafunctional
siloxy units with the ratio of the mono-
- 20 -
~1~4~53 60SI-lS6
functional to tetrafunctional siloxy units is
0.65 - 0.70 and where the silanol content
of the resin is 2% by weight.
Compound H - comprising 90% by weight of a dimethyl-
polysiloxane of a viscosity of lO00 centipoise
at 25 C plus lO~ by weight of a silicone resin
composed pf trimethylsiloxy monofunctional units
and SiO2 tetrafunctional siloxy units with the
ratio of the monofunctional siloxy units to the
tetrafunctional siloxy units is 0.65 - 0.70
and its resin has a silanol content of 2% by
weight.
Compound I - comprising 90% by weight of a dimethyl-
polysiloxane polymer of lO0 centipoise
viscosity at 25C plus 10% by weight of
a silicone resin composed of trimethyl
siloxy momofunctional units and SiO2
tetrafunctional siloxy units with a
ratio of the monofunctional siloxy units
to the tetrafunctional siloxy units is
0.65 - 0.70 and the resin has a silanol
content of 2% by weight.
Compound J ~ comprising 90% by weight of a dimethylpoly-
siloxane polymer of 350 centipoise viscosity
at 25C plus 10% by weight of a silicone
`~ resin composed of a trimethyl siloxy
monofunctional units and SiO2 tetra-
functional siloxy units with a ratio of
the monofunctional siloxy units to the
tetrafunctional siloxy units is 0.65 -
0.70 and the resin has a silanol content
of 2~ by weight.
- 21 -
1~4~3 60SI-156
As will be explained below that in all the above com-
pounds which were prepared by the procedure set forth herein-
below, that in such compounds prior to the mixing and during
the mixing that such compounds were prepared from a solution
of the silicone resin in xylene or toluene in which the
dissolved resin was present and that the foregoing weight
per cents of the silicone resin given above for Compounds A
thru K were in terms of silicone resin solids.
EXAMPLE II
The above compounds wherein there is present a silicone
resin in the compound were prepared as follows:
Into a three-necked flask equipped with a stirrer,
thermometer, heating mantel, take-off head and condensor
there was incorporated 1890 parts of the dimethylpolysiloxane
oil and 353 parts of the solution of the silicone resin which
was normally present in a 50% solid solution in the solvent.
The resulting ingredients were mixed at room temperature.
The xylene or toluene solvent that was present to dissolve
the silicone resin prior to mixture was then stripped off by
vacuum and nitrogen sparge after removing the stirrer. The
temperature was raised to 130C to assure complete removal
of the solvent The material was then allowed to cool and
used as is. It can be appreciated the quantities of in-
gredients would vary in accordance with the concentration of
the silicone resin and dimethylpolysiloxane as set forth above
for Compounds A thru K. In the case where a filler was
incorporated into the compound, the procedure for incorporating
the filler was as followsO
To a metal breaker there was added 1387.5 parts (92.4
by weight) or 1348 parts (89.9~ by weight) of the fluid
which may comprise as one having a silicone resin in it or a
fluid having no silicone resin in it and to such a fluid
60SI-156
11~44~
there was added 112.5 parts (7.5% by weight) or 150 parts
(10~ by weight) of a filler and 2 grams of oleic acid were
charged to the mixture, the oleic acid being a wetting agent
for the filler and agitation was carried out under high shear.
The temperature of the mixture was raised to 150C for 1 hour.
The compound was then passed through a Manton-Gaulin homogenizer
equipped with a conical valve and valve seat and operating at
8000 psi to reduce particle size and aid dispersion of the
filler in the fluid. The compound was then further agitated
150C for 3 hours. It was then cooled to room temperature
under agitation and used as is. The above procedures were
given to be exemplary of the manner in which the compounds
and fluids could be prepared whose anti-foam values are given
in Table I and II below. Such procedures were actually
utilized in the instant case to prepare the anti-foam compound
with or without a silicone resin and with the incorporation
of a filler in the composition. Results of the testing of
the foregoing compounds and fluids is set forth in Table I
and II below utilizing the procedures defined above. In
Table I below there is given both the viscosity of the final
anti-foam composition as well as the anti-foam value of the
composition. The main difference is in the test between Table
I and Table II below is that precipitated silica was utilized
in the test in Table II while fumed silica was utilized in
the tests of Table I. The results are set forth as follows:
- 23 -
.il~4~53 60SI-156
TABLE I
Anti-Foam Compounds
Silicone Fumed Silica (cps.) Anti-foam
Compound Fluid Resin Filler Level Viscosity Value mg/ml
I A No 5 320 .60
II A No 7.5 400 .70
III A No10.0 520 .70
IV K Yes7.5 776 .72
V K Yes10.0 988 .39
VI B No 7.5 1070 .89
VIII E Yes7.5 1710 .31
IX F Yes7.5 1340 .65
X G Yes7.5 1466 .50
XI C No 7.5 3950 .70
XII C No10.0 6700 .62
XIII H Yes7.5 16,700 .35
XTV H Yes10.0 13,900 .42
. ' '.
- 24 -
,, ~
.. . . . .
11~4~S~ 60SI-156
TABLE II
Anti-Foam Compounds
Silicone Precipitated (cps.) Anti-foam
Compound Fluid Resin Silica Filler Viscosity Value m~.ml
XV B No 7.5 760 .39
XVI B No 10.0 1070 .34
XVII J Yes 7.5 1400 .27
XVIII J Yes 10.0 1700 .32
- 25 -
,
3 60SI-156
The above results show the incorporation of a silicone
resin in accordance with foregoing disclosure in combination
with a high filler loading produces an anti-foam composition
with excellent anti-foam values.
EXAMPLE III
The compounds and fluids of Example I above were
then formed into emulsions and tested against for the emulsion
stability as explained previously as well as for the anti-
foam values in accordance with the procedures previously
described. The exemplary procedure that was utilized to
prepare the emulsions in the instant experiments is as
follows:
To a steel breaker 82.4 parts of sorbitan monostearate
to 57 parts of polyoxyethylene stearate and 180 parts of
Part I water were charged and heated to 65C under high
shear agitation. To this mixture there was added 315 parts of
the anti-foam compound that was prepared as set forth in
Example I, which compound was slowly added to the breaker while
maintaining the temperature at 65C during the addition.
Mixing was then continued until premix was uniform. Then
362.5 parta of additional water which was heated to 65C was
added to the premix under high shear agitation. Mixing was
continued while cooling to 57C. The anti-foam emulsion was
then milled on a two inch Manton-Gaulin Colloid Mill at a ~-
setting of 4 mils. The resultant emulsion was then cooled
to room temperature under agitation. To this mixture and
during the cooling period there was added 2 grams sorbic
acid as a bactericide. The emulsion was tested as is. As
has been stated previously, the above procedure was an ex-
emplary pxocedure that was utilized in actual practice to
; prepare the anti-foam emulsions from the silicone compounds
and fluids that were prepared as explained aboYe in Example I.
- 26 -
'~
- 6OSI-156
~1~4~53
The actual weights that were utilized as can be appxeciated
will vary depending on the Ingredients present as set forth
in Tables III and IV below where the anti-foam values are
given. Thus, Tables III and IV below set forth the anti-
foam values and the stability of the emulsions which were
tested in accordance with the procedures described previously.
Again, the main difference between the results in Table III
and Table IV is that the filler that was utilized in the com-
pounds of Table III was fumed while the filler utilized in
the compounds and amulsions of Table IV was precipitated
silica. With respect to the centrifuge stability column given
below, the "T" indicates the value in milliliters of oil
appearing at the top of the sample that was tested while the
"B" value indicates the milliliters of sediment locatea at
the bottom of the vial after the foam stability test. "T" in
the results column indicates trace amounts.
TABLE III
Anti-foam Emulsions
Fumed Cehtrifuge
Silicone Silica Stability Anti-foam
Emulsio~ Compound ResinFiller T B Value mg/ml.
I No 5 2 1 .54
21 II No 7.5 2 T .72
: 22 III No10.0 T T . 65
23 IV Yes7.5 T T . 49
24 V Yes10.0 T T . 61
VI No 7.5 5 T .64
26 VII Yes7.5 5 .5 .48 ;~
27 VIII Yes7.5 5 .5 .34
28 XI No 7.5 10 T .53
29 XII No10.0 T 2 .40
XIII Yes7.5 T T .44
; 31 XIV Yes10.0 T 4 .30
- 27 -
.
1104~53 60SI-156
TABLE IV
Anti-foam Emulsions
Precip. Centrifuge
Silicone Silica Stability Anti-foam
Emulsion Compound Resin Filler T B Value mg/ml.
32 XV No 7.5 6 10 .24
33 XVI No10.0 2 T . 21
34 XVII Yes7. 5 T 10 .17
XVIII Yes10.0 T 18 . 62
The results set forth in Table III and IV above indicate
the stable emulsions can be formed utilizing the silicone
resins of the instant case. Accordingly, as the results
indicate silicone resins composed of monofunctional and
: tetrafunctional siloxy units can be utilized with advantage
in anti-foam compounds and anti-foam emulsions to produce
anti-foam compounds and emulsions of improved anti-foaming
propertles.
-''."
- 28 -
