Colloid systems and wetting agents; subcombinations thereof; pro – Continuous liquid or supercritical phase: colloid systems;... – Aqueous continuous liquid phase and discontinuous phase...
Reexamination Certificate
2002-05-15
2003-12-09
Metzmaier, Daniel S. (Department: 1712)
Colloid systems and wetting agents; subcombinations thereof; pro
Continuous liquid or supercritical phase: colloid systems;...
Aqueous continuous liquid phase and discontinuous phase...
C516S076000, C516S928000, C516S929000, C524S588000
Reexamination Certificate
active
06660778
ABSTRACT:
This application is an application under 35 U.S.C. Section 371 of International Application Number PCTJFR00/02338 filed on Aug. 18, 2000.
The present invention relates to a method of grindlessly emulsifying a silicone in water.
The emulsification methods most commonly used in the art are methods which involve mixing an aqueous phase and an oily phase with grinding, i.e., under high shear. High-shear conditions are generated, for example, by stirring in a colloidal grinder.
The major drawback of these methods is that they make it difficult if not impossible to produce heat-sensitive formulations in the form of emulsions.
The high shear involved in the methods of emulsification with grinding causes heating of the phases present and subjects their constituents to high temperatures. For example, when the oily phase comprises an organic solvent in addition to the silicone, the heating of the oily phase may cause the surfactant to dissolve in the oily phase, thereby promoting the formation of an inverse emulsion of water-in-oil type. In the context of the invention, however, the aim is to prepare direct emulsions of the oil-in-water type.
By heat-sensitive formulation is meant a formulation comprising one or more heat-sensitive constituents.
Within the context of the invention, a heat-sensitive constituent is a compound which is inherently temperature sensitive or is made temperature sensitive by its combination with other compounds that are present in the formulation.
Within the art, a distinction is made between direct emulsification methods and inverse emulsification methods. The direct emulsification methods for obtaining emulsions of oil-in-water type are methods in which, throughout its preparation and up until the time of its formation, the emulsion is a direct emulsion, i.e., an oil-in-water emulsion.
The inverse emulsification methods for obtaining emulsions of oil-in-water type involve the initial formation of a water-in-oil emulsion (commonly designated an inverse emulsion), then the inversion of this emulsion, whereby an oil-in-water emulsion is obtained.
The direct emulsification methods are not suitable for the industrial-scale preparation of emulsions with a high oil concentration.
In this case, in effect, the oily phase must be added slowly to the aqueous phase, this being undesirable from the standpoint of operating deadlines.
The inverse emulsification methods that are known in the art do not all lead to the preparation of fine, monodisperse emulsions.
The method of the invention aims to solve all of these problems by allowing the emulsification of viscous or slightly viscous oils in the presence where appropriate of one or more heat-sensitive constituents, with control of the particle size and of the polydispersity. The emulsions obtained by this method may have a very high oil concentration and may exhibit a very high weight ratio of oil to surfactant, of more than 9/1, for example.
More specifically, the method of the invention, which is a method of grindlessly emulsifying a silicone in water, comprises the steps of:
a) preparing a primary emulsion of oil-in-water type comprising said surfactant and said silicone under a shear of less than 100 s
−1
by adding an aqueous phase to an oily phase comprising said silicone, the proportion of oily phase in the primary emulsion being less than the maximum proportion P
max
above which addition of the aqueous phase to the oily phase does not make it possible to prepare an emulsion of oil-in-water type, and the weight ratio of surfactant to water in the primary emulsion being such that a mixture in this same ratio of the water and the surfactant leads to an organized phase to the exclusion of an inverse phase;
b) enriching the emulsion thus prepared with an oily enrichment phase comprising said silicone by mixing said emulsion with said oily enrichment phase under a shear of less than 100 s
−1
, the amount of oily enrichment phase being less than the maximum amount above which addition of said emulsion to said oily phase does not make it possible to prepare an emulsion of oil-in-water type, thereby giving an emulsion of oil-in-water type; and
c) where appropriate, repeating the implementation of step b) one or more times until the desired concentration of surfactant and/or silicone in the final emulsion is obtained and/or until the desired particle size is obtained.
The silicones which can be emulsified by the method of the invention are, for example, polyorganosiloxane oils, gums or resins.
Among the polyorganosiloxane oils and gums which can be employed, mention may be made of those consisting of units and formula:
R′
3-a
R
a
SiO
1/2
and R
2
SiO
in which formulae:
a
is an integer from 0 to 3
the radicals R are identical or different and represent:
a saturated or unsaturated aliphatic hydrocarbon group containing from 1 to 10 carbon atoms;
an aromatic hydrocarbon group containing from 6 to 13 carbon atoms;
a polar organic group bonded to the silicon by a Si—C or Si—O—C bond;
a hydrogen atom:
the radicals R′ are identical or different and represent
an OH group
an alkoxy or alkenyloxy group containing from 1 to 10 carbon atoms;
an aryloxy group containing from 6 to 13 carbon atoms;
an acyloxy group containing from 2 to 13 carbon atoms;
a ketiminoxy group containing from 3 to 8 carbon atoms;
an amino- or amido-functional group containing from 1 to 6 carbon atoms and bonded to the silicon by a Si—N bond;
preferably at least 80% of the radicals R of said oils representing a methyl group.
Among the polyorganosiloxane resins which can be employed, mention may be made of those consisting of units of formulae:
RSiO
3/2
(T unit) and/or SiO
2
(Q unit)
in association with units of formula:
R′
3-a
R
a
SiO
1/2
(M unit) and/or R
2
SiO (D unit)
in which formulae
a
, R and R′ are as defined above.
These resins are generally of the MQ, MDQ, TDM, TD or MT type.
As examples of aliphatic or aromatic hydrocarbon radicals R, mention may be made of the following groups:
alkyl, preferably optionally halogenated C
1
-C
10
alkyl, such as methyl, ethyl, octyl or trifluoropropyl;
alkoxyalkylene, preferably C
2
-C
10
, more preferably C
2
-C
6
, such as —CH
2
—CH
2
—O—CH
3
;
—CH
2
—CH
2
—O—CH
3
;
alkenyls, preferably C
2
-C
10
alkenyl, such as vinyl, allyl, hexenyl, decenyl or decadienyl;
alkenyloxyalkylene such as —(CH
2
)
3
—O—CH
2
—CH═CH
2
, or alkenyloxyalkoxyalkyl such as —(CH
2
)
3
—OCH
2
—CH
2
—O—CH═CH
2
, in which the alkyl moieties are preferably C
1
-C
10
and the alkenyl moieties are preferably C
2
-C
10
;
aryls, preferably C
6
-C
13
, such as phenyl.
As examples of polar organic groups R, mention may be made of the following groups:
hydroxy-functional groups such as alkyl groups substituted by one or more hydroxyl or di(hydroxyalkyl)amino groups and optionally interrupted by one or more divalent hydroxyalkylamino groups. By alkyl is meant a preferably C
1
-C
10
, more preferably C
1
-C
6
, hydrocarbon chain;
examples of these groups are —(CH
2
)
3
—OH;
—(CH
2
)
4
N(CH
2
CH
2
OH)
2
;
—(CH
2
)
3
—N(CH
2
CH
2
OH)—CH
2
—CH
2
—N(CH
2
CH
2
OH)
2
:
amino-functional groups such as alkyl substituted by one or more amino or aminoalkylamino groups in which alkyl is as defined above; examples thereof are —(CH
2
)
3
—NH
2
; (CH
2
)
3
—NH—(CH
2
)
2
NH
2
;
amido-functional groups such as alkyl substituted by one or more acylamino groups and optionally interrupted by one or more divalent alkyl-CO—N< groups in which alkyl is as defined above and acyl represents alkylcarbonyl; one example is the group —(CH
2
)
3
—N(COCH
3
) —(CH
2
)
2
NH(COCH
3
);
carboxy-functional groups such as carboxyalkyl optionally interrupted by one or more oxygen or sulfur atoms, in which alkyl is as defined above; one example is the group —CH
2
—CH
2
—S—CH
2
—COOH.
As examples of radicals R′, mention may be made of the following groups:
alkoxy, preferably C
1
—C
10
, more preferably C
1
-C
6
, such as methoxy, ethoxy or octyloxy;
alkenyloxy, preferably C
2
-C
10
, more preferably C
2
-C
6
;
aryloxy, preferably C
6
-C
Durand Nicolas
Maze Hervé
Mercier Jean-Michel
Metzmaier Daniel S.
Rhodia Chimie
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