Transparent aqueous compositions comprising hydrophobic...

Details Transparent aqueous compositions comprising hydrophobic... Transparent aqueous compositions comprising hydrophobic...

2003-07-09

2004-10-12

Moore, Margaret G. (Department: 1712)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Cosmetic, antiperspirant, dentifrice

C424S070120, C524S588000

Reexamination Certificate

active

06803050

ABSTRACT:

The present invention relates to optically transparent aqueous compositions containing hydrophobic silicone oil and a comparably low amount of wash-active matter, the compositions being suitable as a hair treatment composition such as a shampoo.
Due to their very low surface tension, the spreadability of silicone oils on most surfaces such as ceramics, textiles, paper, skin, and hair, is excellent. In the field of personal care products, silicone oils are used because of their hair and skin smoothing properties, hair gloss enhancing properties and skin feel improving (non-oily, silky skin feel) properties. For many decades they are therefore ingredients in hairsprays, conditioners, colorants and sun protecting creams. In cosmetic rinse-off products like shampoos they appeared in the 1980ies and could obtain a considerable market share in the early 1990ies in the so-called “two-in-one” shampoos. These shampoos contain emulsified silicone oils. Silicone oil emulsions, however, show problems with respect to compatibility and stability, they show a strong foaminess reducing effect and furthermore they are generally not transparent. This is why hydrophilic silicone polyethers have been introduced into the market. But apart from their generally higher price, the conditioning effect of hydrophilic silicone polyethers on skin and hair is generally much lower than of the hydrophobic silicone oils.
In view of these problems, attempts have been made to provide aqueous compositions containing hydrophobic silicone oil, the silicone oil being in a solubilized or micro-emulsified state. U.S. Pat. No. 6,013,683 describes a microemulsion containing 40 to 95 wt. % of a short chain linear siloxane and water, and 5 to 60 wt. % of non-ionic and/or cationic surfactants. However, the microemulsions disclosed in this patent are only transparent in a very narrow temperature range and easily become turbid when added to aqueous solutions.
EP 0 529 883 B1 discloses hair shampoo compositions containing sodium lauryl ether sulfate and cocoamido propyl betaine as surfactants and 1.0 wt.-% of silicone oil. The silicone oil was added as micro-emulsion prepared by an emulsion polymerization technique. Hence, EP 0 529 883 B1 does not disclose aqueous compositions containing silicone oil which may be easily prepared.
On the other hand, the inventors of the present invention previously published a method allowing the easy incorporation of silicone oil into shampoos (H. Denzer, R. Jansen, M. Reininghaus in “Parfümerie und Kosmetik”; June 1999 pages 18-20). However, the method only allowed for the incorporation of comparably low amounts of silicone oil such as 0.5 wt.-% when using wash-active matter within the range of 15-40 wt.-%. Higher amounts of hydrophobic silicone oil could only be solubilized by increasing the amount of wash-active matter which is, however, not acceptable for dermatological and environmental reasons as well as for price reasons.
In view of these drawbacks of the prior art, it is the object underlying the present invention to provide an easily preparable, optically transparent aqueous composition being suitable as hair shampoo containing an increased amount of hydrophobic silicone oil.
This object of the present invention is solved by the provision of an optically transparent aqueous composition comprising
(a) a hydrophobic silicone oil in an amount of 1-3 wt.-% with respect to the total weight of the composition;
(b) a solubilizer for the silicone oil; and
(c) an anionic surfactant;
wherein the weight ratio of component (b) to component (a) is in the range of 1:1 to 10:1; and wherein the total amount of the components (b) and (c) is in the range of 10-25 wt.-% with respect to the total weight of the composition.
A hydrophobic silicone oil is generally a silicone oil which is soluble in paraffinic oil at 25° C. Hydrophobic silicone oils to be used according to the present invention include both volatile and non-volatile silicone oils.
Specific examples include a cyclic methyl siloxane having the formula {(CH
3
)
2
SiO}
x
in which x is 3-6, or short chain linear methyl siloxanes having the formula
((CH
3
)
2
SiO{(CH
3
)
2
SiO}
y
Si(CH
3
)
3
in which y is 0-5.
Some suitable cyclic methyl siloxanes are hexamethylcyclotrisiloxanes (D
3
), a solid with a boiling point of 134° C. and the formula {(Me
2
)SiO}
3
; octamethylcyclotetrasiloxane (D
4
) with a boiling point of 176° C., a viscosity of 2.3 mm
2
/s, and the formula {(Me
2
)SiO}
4
; decamethylcyclopentasiloxane (D
5
) (cyclomethicone) with a boiling point of 210° C., a viscosity of 3.87 mm
2
/s, and the formula {(Me
2
)SiO}
5
; and dodecamethylcyclohexasiloxane (D
6
) with a boiling point of 245° C., a viscosity of 6.62 mm
2
/s and the formula {(Me
2
)SiO}
6
.
Some suitable short linear methyl siloxane are hexamethyldisiloxane (MM) with a boiling point of 100° C., viscosity of 0-65 mm
2
/s, and formula Me
3
SiOMe
3
; octamethyltrisiloxane (MDM) with a boiling point of 152° C., viscosity of 1.04 mm
2
/s, and formula Me
3
SiOMe
2
SiOsiMe
3
; decamethyltetrasiloxane (MD
2
M) with a boiling point of 194° C., viscosity of 1.53 mm
2
/s, and formula Me
3
SiO(MeSiO)
2
SiMe
3
; dodecamethylpentasiloxane (MD
3
M) with a boiling point of 229° C., viscosity of 2.06 mm
2
/s; and formula Me
3
SiO(Me
2
SiO)
3
SiMe
3
; tetradecamethylhexasiloxane (MD
4
M) with a boiling point of 245° C., viscosity of 2.63 mm2/s, and formula Me
3
SiO(Me
2
SiO)
4
SiMe
3
; and hexadecamethylheptasiloxane (MD
5
M) with a boiling point of 270° C., viscosity of 3.24 mm
2
/s, and formula Me
3
SiO(Me
2
SiO)
5
SiMe
3
.
Furthermore, long chain linear siloxanes such as phenyltrimethicone, bis(phenylpropyl)dimethicone, dimethicone, and dimethiconol are also included.
The amount of the hydrophobic silicone oil is 1-3 wt.-%, preferably 1.5 wt. % to 3 wt. % with respect to the total weight of the composition.
The composition of the present invention further contains a solubilizer for the silicone oil. The term “solubilizer”, in the context of the present invention, refers to a surfactant which allows the solubilization of the hydrophobic silicone oil or the formation of a micro-emulsion of the hydrophobic silicone oil in an aqueous phase. Solubilization is defined as the spontaneous dissolving of a substance by the reversible interaction with the micelles of a surfactant in a solvent to form a thermodynamically stable isotropic solution with reduced thermodynamic activity of the solubilized material (see “Surfactants and Interfacial Phenomena”, by Milton T. Rosen, ed. John Wiley & Sons (1978), Chapter 4, page 123). This isotropic solution is generally a single phase clear microemulsion which forms spontaneously in the sense that it does not require a high energy input by means of high shear devices. Thus, a turbine, impeller, colloid mill, homogenizer, or sonicator, is not required to form these systems. It is only necessary that the appropriate amounts of the three components water, silicone oil, and solubilizer be added to a suitable container, and the container is either hand shaken, or gently stirred by means of a laboratory magnetic stirrer at a temperature below 30° C. Of course, the components can be mixed or sheared with more energy input, and the clear single phase system will still be obtained, but no advantage results from such additional energy usage.
The solubilization property of a surfactant or surfactant mixture can be easily determined by placing the surfactant/surfactant mixture, silicone oil, such as Cyclomethicone and possibly water in a vessel, e.g. in a total volume of 100 ml. The weight ratio of solubilizer to silicone oil may be in the range of 1:1 to 12:1. Then, a magnetic bar is introduced into the vessel, and the vessel is placed on top of a magnetic stirrer such as IKAMAG (supplied by Janke&Kunkel, Germany). Subsequently, the mixture is stirred at a maximum of 400 RPM, preferably 200 RPM at a temperature of 20° C. or less for some minutes, e.g. 5 minutes. 400 RPM correspond approximately to an energ

Affiliated with

Also associated with

Rating

Transparent aqueous compositions comprising hydrophobic... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Transparent aqueous compositions comprising hydrophobic..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Transparent aqueous compositions comprising hydrophobic... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3321294