Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
2002-01-17
2004-10-19
Padmanabhan, Sreeni (Department: 1617)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
C424S070100, C424S070110, C424S070160, C424S078020, C424S078030, C424S078180
Reexamination Certificate
active
06805872
ABSTRACT:
The present invention relates to the cosmetic use of block ethylenic copolymers of elastic nature and also to cosmetic compositions containing such copolymers.
Certain block copolymers are known as being thermoplastic elastomers, that is to say polymers combining the elasticity of a vulcanized rubber with hot plasticity or hot meltability (Thermoplastic Elastomers: Comprehensive Review, Legge N. R., Holden G., published by Hense Munich, 1987).
The elastic properties of this type of polymer derive from the combination of at least one “flexible” block providing the elastic properties, and of at least one “rigid” block providing, by self-association, the reversible physical crosslinking of the macromolecular chains.
Patent application WO 98/38981 discloses hydrocarbon-based solvent gels containing thermoplastic elastomers and especially styrene/butadiene/styrene, styrene/isoprene/styrene and styrene/ethylene/butylene/styrene block copolymers sold by Shell Chemical Company under the name Kraton®. In these hydrocarbon-based media, the copolymers act as thickener and gelling agent, which does not allow them to be formulated in high contents.
These polymers also have the drawback of being insoluble in most of the solvents used cosmetically, such as alcohols, ethers, esters and/or water. Moreover, the synthesis of these block copolymers is carried out by anionic polymerization, which is a method that is difficult to implement.
New free-radical polymerization techniques have recently been developed, such as controlled polymerization (“New Method of Polymer Synthesis”, Blackie Academic & Professional, London, 1995, volume 2, page 1, or
Trends Polyn. Sci
. 4, page 183 (1996) by C. J. Hawker), and especially atom-transfer free-radical polymerization (
JACS
, 117, page 5614 (1995), by Matyjasezwski et al.). These techniques now make it possible to perform the free-radical synthesis of a very wide variety of block copolymers “to order” under operating conditions that are more readily industrializable than was the case for anionic or cationic polymerization, and thus allow an adjustment of the physicochemical properties of the polymers according to the intended use.
By incorporating these novel block copolymers into cosmetic compositions, the Applicant has discovered that certain block ethylenic copolymers of elastic nature described in greater detail hereinbelow have very advantageous cosmetic properties. In general, they produce non-stick systems. When used in hair lacquers, they improve both the styling power and the suppleness of the hair lacquers. They increase the impact strength of nail varnishes and improve the staying power of a wide variety of make-up compositions if without causing the user any discomfort.
One subject of the invention is, consequently, the cosmetic use of block ethylenic copolymers of elastic nature, comprising
(a) at least one rigid block having a glass transition temperature (T
g
) of greater than or equal to 20° C., consisting of units derived from one or more ethylenic monomers, and
(b) at least one flexible block having a glass transition temperature (T
g
) of less than 20° C., consisting of units derived from one or more ethylenic monomers,
said copolymers allowing the production of a film having an instantaneous recovery of between 5% and 100% with the exclusion of block copolymers having flexible blocks consisting exclusively of ethylene, propylene, butylene, butadiene and/or isoprene units.
The subject of the invention is also cosmetic compositions comprising these block ethylenic copolymers of elastic nature.
Another subject of the invention is the use of the block ethylenic copolymers of elastic nature comprising at least one rigid block and having a glass transition temperature (T
g
) of greater than or equal to 20° C. and at least one flexible block having a glass transition temperature (T
g
) of less than 20° C., to improve the suppleness and the styling power of a hair lacquer, to increase the impact strength of a nail varnish or to improve the staying power of a make-up composition.
Other subjects will become apparent on reading the description and the examples which follow.
The expression “units derived from a monomer” as used in the present invention denotes the constituent units of the polymer obtained by polymerization of said monomer.
The block ethylenic copolymers used cosmetically in accordance with the invention are copolymers comprising at least two blocks of monomers that differ as regards their glass transition temperature, one having a glass transition temperature which is greater than or equal to room temperature (20° C.), and the other having a glass transition temperature which is less than room temperature. The first type of block is generally termed “rigid” since, at room temperature, this part of the polymer is in the glassy state, whereas the second type of block, which is in the plastic state at room temperature, is referred to as being “flexible”.
As mentioned above, these block ethylenic copolymers of elastic nature are preferably obtained by controlled free-radical polymerization described, inter alia, in “New Method of Polymer Synthesis”, Blackie Academic & Professional, London 1995, volume 2, page 1, or in
Trends Polym. Sci
. 4, page 183 (1996) by C. J. Hawker.
Controlled free-radical polymerization makes it possible to reduce the deactivation reactions of the growing free-radical species, in particular the termination step, these being reactions which, in standard free-radical polymerization, interrupt the growth of the polymer chain in an irreversible and uncontrolled manner.
In order to reduce the probability of the termination reactions, it has been proposed to transiently and reversibly block the growing free-radical species by forming “dormant” active species in the form of a bond with a low dissociation energy.
Thus, the polymerization may be performed according to the atom-transfer technique or by reaction with a nitroxide, or alternatively according to the “reversible addition-fragmentation chain transfer” technique.
The atom-transfer free-radical polymerization technique, also known by the abbreviation ATRP, consists in blocking the growing free-radical species in the form of a bond of C-halide type (in the presence of a metal/ligand complex). This type of polymerization is reflected by a control of the mass of the polymers formed and by a low polydispersity index.
In general, the atom-transfer free-radical polymerization is performed by polymerization of one or more free-radical-polymerizable monomers, in the presence
of a primer having at least one transferable halogen atom,
of a compound comprising a transition metal capable of participating in a reduction step with the primer and a “dormant” polymer chain, and
of a ligand which may be chosen from compounds comprising a nitrogen (N), oxygen (O), phosphorus (P) or sulfur (S) atom, capable of coordinating via &sgr; bonding to said compound comprising a transition metal, the formation of direct bonds between said compound comprising a transition metal and the polymer in formation being avoided.
The halogen atom is preferably a chlorine or bromine atom.
This process is described in particular in patent application WO 97/18247 and in the article by Matyjasezwski et al. published in
JACS
, 117, page 5614 (1995).
The technique of free-radical polymerization by reaction with a nitroxide consists in blocking the growing free-radical species in the form of a bond of C-ONR
1
R
2
type, R
1
and R
2
possibly being independently of each other, an alkyl radical containing from 2 to 30 carbon atoms or together forming, with the nitrogen atom, a ring containing from 4 to 20 carbon atoms such as, for example, a 2,2,6,6-tetramethylpiperidyl ring. This polymerization technique is described especially in the articles “Synthesis of nitroxy-functionalized polybutadiene by anionic polymerization using a nitroxy-functionalized terminator”, published in
Macromolecules
1997, volume 30, pages 4238-4242, and “Macromolecular engineering via living free radical polymerizations” publi
L'Oreal
Nixon & Vanderhye P.C.
Padmanabhan Sreeni
Wells Lauren Q
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