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CROSS REFERENCE TO A RELATED APPLICATION
Applicants claim priority under 35 USC 119 for application P 27 30 923.5
filed July 8, 1977 in the Patent Office of the Federal Republic of
Germany.
BACKGROUND OF THE INVENTION
The field of the invention is emulsions of silicone fluids in water and the
present invention is particularly concerned with an improvement in the
method of making emulsions of dimethyl silicone fluids.
The state of the art of dimethyl silicone fluids and emulsifying methods
therefore may be ascertained by reference to the Kirk-Othmer "Encyclopedia
of Chemical Technology", 2nd Edition, Volume 18 (1959), pp. 221-260 under
the Section Silicones, particularly pp. 237-241 where dimethyl silicone
fluids are disclosed, and p. 249 where emulsions of silicone fluids are
disclosed and British Pat. Nos. 808,193 and 915,787 and U.S. Pat. No.
2,755,194 where emulsifying methods are defined. These references are
incorporated herein.
Water-dilutable oil-in-water emulsions are an especially preferred form of
using the silicone oils or fluids. In this form, they are employed, for
example, to render materials hydrophobic, for defrothing purposes, for the
application of thin films for release purposes, for lustering, for
increasing the slip and for improving the hand of textile materials. As is
known, great difficulties are encountered in the production of finely
dispersed, aqueous silicone oil emulsions (see "Ullmanns Enzyklopaedie der
technischen Chemie" [Ullmann's Encyclopedia of Technical Chemistry] third
edition, 1964, vol. 15, p. 783, fifth paragraph), the disclosure of which
is incorporated herein.
Although several emulsifying methods are known from British Pat. Nos.
808,193 and 915,787 and U.S. Pat. No. 2,755,194, column 2, these operate
with the aid of homogenizing devices and/or with the use of solvents in
addition to the emulsifiers. In spite of the expensive manufacturing
process, these emulsions are generally of insufficient stability with
regard to shelf life. Furthermore, these emulsions, due to their solvent
content, are poorly or not at all suitable for certain usages, such as,
for example, for textile preparations.
SUMMARY OF THE INVENTION
Having in mind the limitations of the prior art, it is an object of the
present invention to provide a method of emulsifying dimethyl silicone
fluids which avoids the complications of homogenizing and the use of
solvents in the production of shelf-stable silicone oil emulsions.
A process has now been discovered for the production of aqueous, finely
dispersed, shelf-stable silicone oil emulsions with the use of
emulsifiers, which is characterized by mixing, under agitation at
temperatures of between 20.degree. and 150.degree. C., dimethyl
polysiloxanes and 0.1-0.3 parts by weight, based on the dimethyl
polysiloxane, of an emulsifier comprising a mono- or diester of
orthophosphoric acid or mixtures thereof, until a clear solution is
obtained; thereupon adding an organic base or alkali up to neutralization;
and subsequently diluting with water.
The emulsifiers comprising monoesters of orthophosphoric acid, diesters of
orthophosphoric acid and mixtures thereof are prepared by the reaction of
(a) 1-n-octanol or 1-n-octenol with P.sub.2 O.sub.5, or
(b) straight-chain primary alcohols or 6-10 carbon atoms with phosphoric
acids or phosphorus halogenides, or
(c) mixtures of primary alcohols of an average molecular weight of 110 to
160, which are straight-chain to an extent of at least 50 molar percent
and contain 1-22 carbon atoms, with phosphoric acids, phosphorus oxides,
or phosphorus halogenides.
Advantageously, the partial ester of orthophosphoric acid according to (c)
has been obtained by the reaction of mixtures of alcohols having 4-14
carbon atoms with inorganic phosphorus compounds.
Preferably, dimethyl polysiloxane and the partial ester of orthophosphoric
acid are mixed together at 75.degree.-90.degree. C.
In a preferred embodiment of the present method, the organic base employed
is a primary, secondary, or tertiary amine of 2-8 carbon atoms.
In another preferred embodiment, the silicone oil is mixed with 0.15-0.2
part by weight of the partial ester of orthophosphoric acid.
The order of adding ingredients is critical and if one does not proceed
along the lines of the present invention, although using as the emulsifier
an alkali salt or amine salt of an orthophosphoric acid partial ester,
unstable emulsions are formed as can be seen from the comparative examples
wherein the dimethyl polysiloxanes, emulsifiers and neutralizing bases are
added simultaneously according to the prior art.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Dimethyl polysiloxanes which are converted according to the present
invention into aqueous, finely dispersed, shelf-stable emulsions exhibit
viscosities of 1 to 500,000 centistokes, especially 100-100,000 cs., at
25.degree. C. They satisfy the general formula (CH.sub.3).sub.3
--SiO[SiO--(CH.sub.3).sub.2 ].sub.n --SiO--(CH.sub.3).sub.3.
According to the invention, the following orthophosphoric acid partial
esters can be used, for example, in the first stage: n-hexyl-, n-hexenyl-,
n-octyl, n-octenyl, n-decyl-, n-decenyl-phosphoric acid mono- and diesters
and mixtures thereof, as well as orthophosphoric acid mono- and diesters
of mixtures of alcohols containing 1-22 carbon atoms.
Specific examples of the esters of orthophosphoric acids of (a) include a
mixture of mono-n-octyl orthophosphoric acid ester and
di-n-octyl-orthophosphoric acid ester, a mixture of mono-n-octenyl
orthophosphoric acid ester and di-n-octenyl orthophosphoric acid ester.
Specific examples of the monoesters and diesters of orthophosphoric acids
of (b) include a mixture of mono-n-hexyl orthophosphoric acid ester and
di-n-hexyl orthophosphoric acid ester; a mixture of mono-n-heptyl
orthophosphoric acid ester and di-n-heptyl orthophosphoric acid ester; a
mixture of mono-n-octyl-orthophosphoric acid ester and di-n-octyl
orthophosphoric acid ester, and a mixture of mono-n-decyl-orthophosphoric
acid ester and di-n-decyl-orthophosphoric acid ester.
Specific examples of the monoesters and diesters of orthophosphoric acids
of (c) include a mixture of orthophosphoric acid monoesters and
orthophosphoric acid diesters of a mixture of 0.7% methanol, 1.3%
n-butanol, 3.2% n-hexanol, 1.1% 2-ethyl-hexanol, 86.4% n-octanol, 5.2%
n-dodecanol and 2.1% n-oleyl-alcohol, prepared by the reaction of the
alcohol-mixture with (a) phosphorus oxichloride (POCl.sub.3), and (b)
phosphorus oxide (P.sub.2 O.sub.5).
Suitable alkalis for the neutralizing components are, for example,
ammonium, potassium, sodium and lithium hydroxides. Especially preferred
are organic bases, for example:
1. primary aliphatic amines, such as ethylamine, n-propylamine,
n-butylamine, pentylamine, isobutylamine, monoethanolamine,
1,3-aminopropanol. Also suitable are primary aliphatic amines, the alkyl
residue of which carries substituents, for example heterocyclically
substituted primary aliphatic amines, such as
N-(3-aminopropyl)-morpholine, N-(3-aminopropyl)-piperidine,
N-(3-aminoethyl)-morpholine, primary aliphatic amines substituted by
alkoxy groups, e.g. diethanolamine, methoxypropylamine, ethoxypropylamine,
methoxyethylamine, 2-phenoxyethylamine, 3-phenoxypropylamine, primary
aliphatic amines substituted by dialkylamino groups, such as
N,N-dimethylaminopropylenediamine, N,N-diethylaminopropylenediamine,
p-aminodimethylaniline;
2. Primary cycloaliphatic amines, such as cyclohexylamine,
cyclopentylamine, benzylamine, aniline;
3. Secondary aliphatic and aromatic amines, such as diethylamine,
diisopropylamine, di-n-butylamine, di-n-hexadecylamine, dibenzylamine,
butylmethylamine, ethylhexadecylamine, N-methylaniline;
4. secondary heterocyclic amines, such as morpholine, piperidine,
pyrrolidine, 2,3-dihydroindole;
5. tertiary amines, such as triethylamine, triisopropylamine,
tributylamine, triethanolamine, N-oxaethylmorpholine,
N-hydroxypropylmorpholine, N-methylmorpholine, pyridine.
Preferably, amines of 2-8 carbon atoms are utilized as the neutralizing
components, such as, for example, monoethanolamine, 1,3-aminopropanol,
methoxypropylamine, morpholine, N-methylmorpholine, diethanolamine,
N-oxaethylmorpholine, diethylamine, diisobutylamine, di-n-butylamine.
The dimethyl polysiloxane and the acidic phosphoric acid partial ester are
mixed, in accordance with the invention, at 20.degree.-150.degree. C.
under agitation. This means that both components can be combined at room
temperature and stirred at this temperature until a clear solution is
produced, or alternatively after the components have been combined at room
temperature they are then heated under agitation and the agitation is
continued at a temperature of up to 150.degree. C. until a clear solution
has been obtained. With the use of elevated temperatures, the clear
solution is formed very rapidly, while the treatment at room temperature
takes a longer period of time.
It is additionally possible to incorporate nonionic products, e.g. of the
type of the alkyl and alkylaryl polyalkylene glycol ethers, into the
highly concentrated, emulsifier-containing dimethyl polysiloxanes, without
substantially affecting their finely dispersed emulsifying effect. The
following examples will explain the mode of operation according to the
present invention:
EXAMPLE 1
A mixture of 75 parts by weight of a phosphoric acid partial ester obtained
by reacting 3 moles of n-octanol with 1 mole of phosphorus pentoxide and
500 parts by weight of a dimethyl polysiloxane oil having a viscosity of
350 cs. at 25.degree. C. was heated under agitation at 100 r.p.m. to
80.degree.-85.degree. C. After about 5 minutes, a clear, viscous liquid
was obtained during further agitation in this temperature range from the
initially turbid mixture; this liquid was cooled to 30.degree.-40.degree.
C. and neutralized with 20 parts by weight of monoethanolamine at the
aforementioned agitating speed. Subsequently 595 parts by weight of water
was added during a period of 15 minutes under agitation at 200 r.p.m.,
thus obtaining a finely dispersed, thinly fluid emulsion which did not
exhibit any changes either in the centrifuge test or in the standing test
over a period of 5 months.
EXAMPLE 1(a)
The procedure of Example 1 was followed, using in place of monoethanolamine
24.0 parts by weight of n-butylamine. A finely dispersed, thinly fluid
emulsion was thus obtained showing no changes either in the centrifuge
test or in the standing test over a period of 5 months.
EXAMPLE 1(b)
The procedure analogously to Example 1 was employed, utilizing 32.0 parts
by weight of cyclobutylamine instead of monoethanolamine. A finely
dispersed, thinly fluid emulsion was produced in this way, which did not
show any changes either in the centrifuge test or in the standing test
over a period of 5 months.
EXAMPLE 1(c)
The process was used as described in Example 1, using in place of
monoethanolamine 23.5 parts by weight of diethylamine, thus obtaining a
finely dispersed, thinly fluid emulsion showing no changes in the
centrifuge test or in the standing test over a period of 5 months.
EXAMPLE 1(d)
The procedure was analogous to Example 1, but using 26.0 parts by weight of
morpholine in place of monoethanolamine, thus producing a finely
dispersed, thinly fluid emulsion which did not show any changes either in
the centrifuge test or in the standing test over a period of 5 months.
EXAMPLE 1(e)
The process was followed analogously to Example 1, but using 31.2 parts by
weight of N-methylmorpholine instead of monoethanolamine. A finely
dispersed, thinly fluid emulsion was obtained which showed no changes in
the centrifuge test or in the standing test over a period of 5 months.
COMPARATIVE EXAMPLE 1
For comparison purposes, 95 parts by weight of emulsifier consisting of 75
parts by weight of a phosphoric acid partial ester obtained by reacting 3
moles of n-octanol with 1 mole of phosphorus pentoxide and 20 parts by
weight of monoethanolamine was mixed with 500 parts by weight of a
dimethyl polysiloxane oil having a viscosity of 350 cs. at 25.degree. C.,
heated under agitation at 100 r.p.m. to 80.degree.-85.degree. C. and then
diluted with 595 parts by weight of water, thus producing a coarsely
dispersed emulsion which separated already after a short period of time.
EXAMPLE 2
Analogously to the mode of operation of the invention in Example 1, an
emulsion was prepared, using in place of the dimethyl polysiloxane oil
with a viscosity of 350 cs. a dimethyl polysiloxane oil with a viscosity
of 1,250 cs. A finely dispersed, thinly fluid emulsion was thus obtained
which showed no changes either in the centrifuge test or in the standing
test over a period of 5 months.
COMPARATIVE EXAMPLE 2
For comparison purposes, the procedure was followed in accordance with
Comparative Example 1, thus obtaining a coarsely disperse emulsion which
separated already after a brief period of time.
EXAMPLE 3
Analogously to the mode of operation according to the invention as set
forth in Example 1, an emulsion was produced, using in place of the
dimethyl polysiloxane oil with a viscosity of 350 cs. a dimethyl
polysiloxane oil having a viscosity of 60,000 cs., thus obtaining a
slightly viscous, finely dispersed emulsion which showed no changes either
in the centrifuge test or in the standing test over a period of 5 months.
COMPARATIVE EXAMPLE 3
For comparison purposes, the procedure was followed as disclosed in
Comparative Example 1, thus producing a coarsely disperse emulsion which
separated already after a short period of time.
EXAMPLE 4
Analogously to the mode of operation described in Example 1 according to
this invention, an emulsion was prepared, using, in place of the
n-octylphosphoric acid partial ester, a reaction product from 3 moles of
an alcohol mixture, having a C number of 6-10 and an average molecular
weight of 130, and 1.05 mole of phosphorus pentoxide. A finely dispersed,
thinly fluid emulsion was thus obtained which showed no changes either in
the centrifuge test or in the standing test over a period of 5 months.
COMPARATIVE EXAMPLE 4
For comparison purposes, the process was followed as set out in Comparative
Example 1, thus obtaining a coarsely disperse emulsion which separated
already after a short period of time.
EXAMPLE 5
Analogously to the procedure of this invention as disclosed in Example 1,
an emulsion was prepared using in place of monoethanolamine 24.5 parts by
weight of 1,3-aminopropanol. A finely dispersed, thinly fluid emulsion was
thus produced which showed no changes either in the centrifuge test or in
the standing test over a period of 5 months.
COMPARATIVE EXAMPLE 5
For comparison purposes, the process was followed as indicated in
Comparative Example 1, thus obtaining a coarsely disperse emulsion which
separated already after a short period of time.
EXAMPLE 6
Analogously to the mode of operation according to the invention as
disclosed in Example 1, a mixture of 500 parts by weight of a dimethyl
polysiloxane oil with a viscosity of 60,000 cs. at 25.degree. C., 50 parts
by weight of n-octylphosphoric acid partial ester according to Example 1,
and 25 parts by weight of an ethoxylation product from nonyl phenol and 3
moles of ethylene oxide was treated until a clear solution was obtained
and then neutralized with 14.6 parts by weight of monoethanolamine.
Subsequently, 595 parts by weight of water was gradually stirred into the
mixture, thus obtaining a finely dispersed, thinly fluid emulsion which
showed no changes either in the centrifuge test or in the standing test
over a period of 3 months.
Accordingly, the process of this invention makes it possible to prepare
shelf-stable silicone oil emulsions without the addition of solvents and
without homogenization.
The emulsions obtained in accordance with this invention are universally
useful, since they do not contain any solvent. Furthermore, the
preparation of these emulsions requires substantially less expenditure, as
compared with the prior art, since the homogenizing stage is eliminated.
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