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
2001-09-24
2003-11-25
Szekely, Peter (Department: 1714)
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...
C524S376000, C524S474000, C524S593000
Reexamination Certificate
active
06653397
ABSTRACT:
The present invention relates to cosmetic and dermatological preparations, in particular those of the water-in-oil type, to processes for their preparation and to their use for cosmetic and medicinal purposes.
The present invention relates, in a particular embodiment, to cosmetic or pharmaceutical preparations with an improved feel on the skin, reduced feeling of stickiness, to processes for their preparation, and to the use of active ingredients for reducing the feeling of stickiness of cosmetic preparation.
The human skin is man's largest organ and performs a number of vital functions. Having an average surface area of about 2 m
2
in adults, it has a prominent role as a protective and sensory organ. The purpose of this organ is to transmit an average mechanical, thermal, actinic, chemical and biological stimuli. In addition, it has an important role as a regulatory and target organ in human metabolism.
The main aim of skin care in the cosmetics sense is to strengthen or rebuild the skin's natural function as a barrier against environmental influences (e.g. dirt, chemicals, microorganisms) and against the loss of endogenous substances (e.g. water, natural fats, electrolytes), and also to assist its horny layer in its natural regeneration ability where damage has occurred.
If the barrier properties of the skin are impaired, increased resorption of toxic or allergenic substances or infection by microorganisms may result, leading to toxic or allergic skin reactions.
Another aim of skin care is to compensate for the loss by the skin of sebum and water caused by daily washing. This is particularly important if the natural regeneration ability is inadequate. Furthermore, skin care products should protect against environmental influences, in particular against sun and wind, and delay skin aging.
Medicinal topical compositions usually comprise one or more medicaments in an effective concentration. For the sake of simplicity, in order to clearly distinguish between cosmetic and medicinal use and corresponding products, reference is made to the legal provisions in the Federal Republic of Germany (e.g. Cosmetics Directive, Foods and Drugs Act).
Emulsions are generally taken to mean heterogeneous systems which consist of two liquids which are immiscible or miscible with one another only to a limited extent, which are usually referred to as phases. In an emulsion, one of the two liquids is dispersed in the form of very fine droplets in the other liquid.
If the two liquids are water and oil, and oil droplets are very finely dispersed in water, this is an oil-in-water emulsion (O/W emulsion, e.g. milk). The basic character of an O/W emulsion is determined by the water. In the case of a water-in-oil emulsion (W/O emulsion, e.g. butter), the principle is reversed, the basic structure being determined here by the oil.
The person skilled in the art is of course aware of a large number of ways to formulate stable W/O preparations for cosmetic or dermatological use, for example in the form of creams and ointments which can be spread in the range from room temperature to skin temperature, or as lotions and milks, which are more likely flowable in this temperature range. However, there are not many formulations in the prior art which are of sufficiently low viscosity that they would, for example, be sprayable.
In addition, low-viscosity preparations of the prior art frequently have the disadvantage that they are unstable, and are limited to a narrow field of application or a limited choice of feed materials. Low-viscosity products in which, for example, strongly polar oils—such as the plant oils otherwise frequently used in commercially available products—are sufficiently stabilized are therefore currently not on the market.
The term “viscosity” means the property of a liquid to resist the mutual laminar displacement of two neighboring layers (internal friction). This so-called dynamic viscosity is nowadays defined according to &eegr;=&tgr;/D ad the ratio of shear stress to the velocity gradient perpendicular to the direction of flow. For Newtonian liquids, &eegr; is a material constant having the SI unit Pascal second (Pa.s) at a given temperature.
The quotient v=&eegr;/&rgr; from the dynamic viscosity &eegr; and the density &rgr; of the liquid is referred to as the kinematic viscosity v and is given in the SI unit m
2
/s.
Fluidity (&phgr;) is the inverse of viscosity (&phgr;=1/&eegr;). In the case of ointments and the like, the use value is inter alia co-determined by the so-called tack. The tack of an ointment or ointment base or the like is understood as meaning its property to draw threads of varying lengths when a small sample is removed; accordingly, a distinction is made between short- and long-stretch substances.
Whilst the graphical representation of the flow behavior of Newtonian liquids at a given temperature produces a straight line, in the case of the so-called non-Newtonian liquids considerable deviations often arise, depending on the respective velocity gradient D (shear rate &ggr;) or the shear stress &tgr;. In these cases, the so-called apparent viscosity can be determined which although it does not obey the Newtonian equation, can be used to determine the true viscosity values by graphical methods.
Falling-body viscometry is suitable only for investigating Newtonian liquids and gases. It is based on Stokes's law, according to which for the falling of a sphere through a liquid which flows around it, the dynamic viscosity &eegr; can be determined from:
η
=
2
r
2
(
ρ
k
-
ρ
F1
)
g
9
·
v
where
r=radius of the sphere, v=fall velocity, &rgr;
K
=density of the sphere, &rgr;
F1
=density of the liquid, and g=acceleration of fall.
W/O emulsions with a high water content and a low viscosity which moreover have storage stability, as is required for marketable products, can only be formulated according to the prior art in a very complex manner. Accordingly, the supply of formulations of this type is extremely low. Nevertheless, such formulations have been able to offer the consumer hitherto unknown cosmetic effects.
One object of the present invention was to provide preparations which have a very low viscosity and do not have the disadvantages of the prior art.
A further object of the present invention was to provide preparations which can be laden with a high content of water-soluble and/or water-miscible substances having cosmetic or dermatological effectiveness, without impairing the galenical quality or other properties of the preparations.
Although it is known that the addition of certain substances, for example some selected powder raw materials, in particular talc, reduces this feeling of stickiness or else feeling of greasiness, apart from the fact that this is only rarely achieved completely, such an addition also changes the viscosity of the product in question and reduces the stability.
A further object was therefore to overcome all of these disadvantages of the prior art. In particular, the aim was to provide products with reduced stickiness or greasiness. Products in the field of care cosmetics, decorative cosmetics and pharmacological galenics were likewise to be freed from the described disadvantages of the prior art.
It was a further object of the invention to develop cosmetic bases for cosmetic preparations which are characterized by good skin compatibility.
It was a further object of the present invention to provide products which have the broadest possible diversity of use. For example, it was the aim to provide bases for preparation forms such as cleansing emulsions, face care and body care preparations, but also distinctly medicinal-pharmaceutical presentations, for example preparations against acne and other skin conditions.
According to K. J. Lissant:
The Geometry of High-Internal-Phase-Ratio Emulsions;
Journal of Colloid and Interface Science 22, 462-468 (1966), emulsions with an internal phase of more than 70% are defined as so-called high internal phase emulsion
Bleckmann Andreas
Kröpke Rainer
Beiersdorf AG
Szekely Peter
LandOfFree
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