Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-11-02
2001-04-10
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C525S477000, C525S902000, C424S070120
Reexamination Certificate
active
06214928
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to stable anionic aqueous emulsions of organopolysiloxane particles having a volume average particle diameter (Dv) of at least about 300 nanometers (nm) and consisting essentially of chemically combined aminoorganosiloxy functional units and diorganosiloxy units. More particularly, the present invention is directed to a method involving the reaction of an aqueous acid catalyzed emulsion of organopolysiloxane particles with an amine functional organosilicon material.
There is shown in U.S. Pat. Nos. 5,726,270, 5,856,402, and 5,900,460 to Craig, semi-continuous methods for making acid catalyzed aqueous dispersions of organopolysiloxanes useful in coating applications, including personal care. For example, in the formulation of a silicone-containing hair shampoo, experience has shown that desirable results can be achieved with aqueous dispersions of organopolysiloxane particles having a volume average particle diameter in the range of at least about 300 nanometers to about 1 micron. It has been found that improvements in hair styling with silicone-containing shampoos can be achieved in particular situations as a result of the “smoothing out” effect. It is speculated that silicones in the form of aqueous dispersions of organopolysiloxane particles having an average diameter of at least about 300 nanometers can more readily coat the surface of the hair shaft.
Experience also has shown that further benefits in coating and in personal care applications can be obtained with aqueous dispersions of organopolysiloxane particles if the dispersed particles are modified with a functional group, such as aminoorgano, epoxy, carboxy, or mercapto. However, previous efforts to functionalize such organopolysiloxane particles during their initial formation from cyclic poly(diorganosiloxane) under semi-continuous conditions, often resulted in functionalized organopolysiloxane particles with a volume average particle diameter less than about 300 nanometers. In particular, although an aqueous emulsion of organopolysiloxane particles having a volume average particle diameter of at least about 300 nanometers can be generated under semi-continuous conditions by the acid catalyzed equilibration of cyclic poly(diorganosiloxane) in the absence of the amine functionalized organosilicon source material, efforts to functionalize the particles during the initial particle formation under semi-continuous conditions in the presence of an amine functionalized organosilicon source material typically results in particles having a volume average particle diameter less than about 300 nanometers.
Further, a procedure for making an acid catalyzed aqueous dispersion of organopolysiloxane particles with aminoorgano functional groups involves working with competing anionic and cationic charges. In addition to adversely affecting particle size, amine functionalization efforts also can impact adversely on emulsion stability and acid-catalyzed polymerization rates. In particular, emulsion instability is favored as a result of the presence of aminoorgano functional groups, and anionic silicone emulsion particles as shown by U.S. Pat. No. 5,045,576. A satisfactory method is therefor needed to make stable aqueous emulsions of amine functionalized organopolysiloxane particles having a volume average particle diameter of at least about 300 nanometers using an acid catalyzed process.
BRIEF SUMMARY OF THE INVENTION
In one embodiment, the present invention is an aqueous emulsion of amine functionalized organopolysiloxane particles useful in personal care applications, and having a volume average particle diameter of at least about 300 nanometers.
In another embodiment, the present invention is a substantially stable aqueous emulsion having in a range between about 5% by weight and about 60% by weight solids, comprising amine functionalized organopolysiloxane particles having a volume average particle diameter of at least about 300 nanometers, said particles consisting essentially of in a range between about 50 mole % and about 99 mole % of diorganosiloxy units, chemically combined with in a range between about 50 mole % and about 1 mole % of (aminoorgano)organosiloxy units.
In still another embodiment, the present invention is a method for making an aqueous emulsion of amine functionalized organopolysiloxane particles useful in personal care applications, and having a total solids content in a range between about 5% by weight and about 60% by weight, comprising effecting reaction at a temperature in a range between about 25° C. and about 110° C., and in the presence of an effective amount of an acid catalyst surfactant, between (A) an aqueous emulsion of organopolysiloxane particles having a volume average particle diameter of at least about 300 nanometers, and (B) an amine functionalized organosilicon source material, wherein there is used in a range between about 1 part and about 50 parts by weight of (B ) per 100 parts of (A).
In still another embodiment, the present invention is a method for making a substantially stable aqueous emulsion having in a range between about 5% by weight and about 60% by weight of solids, and comprising amine functionalized organopolysiloxane particles having a volume average particle diameter of at least about 300 nanometers, comprising the steps of:
(1) providing an aqueous emulsion comprising in a range between about 1% by weight and about 50% by weight organopolysiloxane particles having a volume average particle diameter of at least about 300 nanometers, by either,
(a) equilibrating under semi-continuous conditions at a temperature in a range between about 25° C. and about 110° C., an aqueous mixture comprising cyclic poly(diorganosiloxane) and an effective amount of an acid catalyst surfactant to form an aqueous emulsion of organopolysiloxane particles having a volume average particle diameter of at least about 300 nanometers, or
(b) employing an aqueous emulsion of preformed organopolysiloxane emulsion seeds having a volume average particle diameter of at least about 300 nanometers; and
(2) effecting reaction between the organopolysiloxane particles or seeds in the aqueous emulsion of (1), and an amine functionalized organosilicon source material in a range between about 1 part and about 50 parts by weight per 100 parts of such organopolysiloxane particles or seeds.
DETAILED DESCRIPTION OF THE INVENTION
Within the context of the present invention “substantially stable aqueous emulsion” means an emulsion in which the dispersed particles do not appreciably agglomerate during the typical shelf-life of the emulsion. In one of its embodiments “semi-continuous” refers to a process for functionalizing organopolysiloxane particles which employs organopolysiloxane particle seeds prepared in a separate step. In other embodiments, “semi-continuous” refers to a reaction which does not need to be stopped in order to add more reactants.
The present invention is based on the discovery that effective aminoorgano functionalization of dispersed organopolysiloxane particles having a volume average particle diameter of at least about 300 nanometers can be achieved by direct treatment of an acid catalyzed aqueous dispersion of said particles with an amine functionalized organosilicon source material in the form of an aminoorgano functionalized organosilicon member selected from the group consisting of an alkoxysilane, a cyclic poly(diorganosiloxane), and a poly(diorganosiloxane) fluid. Surprisingly, the volume average particle diameter of the resulting aminoorgano functionalized particles is found to be substantially the same as the volume average particle diameter of the starting unfunctionalized organopolysiloxane particles.
In one embodiment, a substantially stable aqueous emulsion of functionalized organopolysiloxane particles with the desired size range is produced by a two-staged, acid-catalyzed semi-continuous/semi-continuous or semi-continuous/batch process whereby the particle size is substantially maintained from the first stage and functionali
Craig Daniel Horace
Morgan Wayne Francis
Bennett Bernadette M.
Dawson Robert
General Electric Company
Ingraham Donald S.
Metzmaier Daniel S.
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