Hair treatment method involving fixing active compounds to...

Details Hair treatment method involving fixing active compounds to... Hair treatment method involving fixing active compounds to...

1999-11-22

2002-03-26

Page, Thurman K. (Department: 1615)

Drug, bio-affecting and body treating compositions

Live hair or scalp treating compositions

C008S401000, C008S405000, C008S431000, C008S432000, C132S202000, C132S208000

Reexamination Certificate

active

06361767

ABSTRACT:

The present invention relates to a novel method for treating hair to endow it with novel appropriate properties.
As is well known in the art, the cosmetic qualities of hair can be improved by applying a variety of compositions based on one or more active compounds to endow it with a variety of properties such as, for example, shine, easy disentangling, volume, hold, suppleness, vitality or softness.
To be properly effective, the active compounds of such compositions should, of course, have a certain affinity for the keratinous fibres of the hair, and should also have good persistence.
In other words, such active compounds should as far as possible remain fixed to the hair in a quantity sufficient to endow it with the desired properties.
However, since such active principles are not irreversibly fixed but are only fixed by adsorption, they are gradually eliminated by desorption during successive washes using shampoo.
To improve the persistence, studies have primarily been based on treatments which tend to cause a large proportion of the active principles to penetrate into the fibres, either by selecting such active principles which have a particular affinity for the fibres, or by modifying the fibres to increase their porosity and encourage penetration.
Thus coloration of hair keratin fibres is known to be improved by carrying out coloration simultaneously with permanent-waving. Reduction of the disulphide bonds of the keratin at depth permits the colorant to penetrate deeper and thus produces a certain durability of coloration.
This type of treatment, however, is not without serious disadvantages as it causes substantial degradation not only of the surface condition of the keratinous fibres, but also of their intrinsic mechanical properties.
As a result of a great deal of research in this field with a regard to remedying the disadvantages encountered until now, it has surprisingly and unexpectedly been shown that excellent results could be obtained when fixing active compounds to keratinous hair fibres without them suffering detrimental degradation. This has been achieved by limiting reactive site formation to only the surface of the keratinous hair fibres using a reducing agent employed under conditions and in proportions such that reactive sites are only generated at the periphery of the surface of the keratinous fibres.
It has actually been shown that the creation of reactive sites only on the surface is sufficient, and that they are remarkably reactive, to result in good fixing of a variety of active compounds by means of covalent bonds, without the original mechanical properties of the hair being substantially modified.
Thus the subject of the present invention is a novel method for treating keratinous hair fibres with a view to endowing them with novel appropriate properties, the method comprising steps consisting in reducing the disulphide bonds of the keratin with a view to generating reactive sites only on the surface to a depth of less than 10 &mgr;m and to covalently fix to said reactive sites at least one active compound capable of endowing the keratinous hair fibres with novel appropriate properties, said active compound comprising at least one reactive function capable of reacting with said sites formed at the surface of the keratinous fibres.
In accordance with the invention, the treatment method can be carried out either in two separate steps, namely reducing the disulphide bonds of the keratin in a first step, and fixing the active compound by covalent bonds in a second step, or in a single step consisting in simultaneously reducing the disulphide bonds of the keratin and fixing the active compound.
In a further aspect, the treatment method of the invention envisages first applying the active compound to the keratinous hair fibres and then reducing the disulphide bonds of the keratin.
The essential characteristic of the method of the invention is to form reactive sites only on the surface of the keratinous hair fibres using a reducing composition.
A variety of conventional reducing agents can be used to this end, but their nature and concentration and method of application must be such that reactive sites are only generated on the surface of the keratinous substrate.
In other words, the reducing composition must not react beyond a depth of 10 &mgr;m, preferably not beyond an average depth of 4 to 5 &mgr;m, approximately corresponding to its cuticle.
These are, of course, average values which can vary depending on the type of treatment and which can thus be substantially lower or substantially higher than those indicated.
The reactive sites generated at the surface of the keratinous fibres are nucleophilic in nature and are essentially thiol functions.
In accordance with the invention, the reduction can be such that it generates between 0.1% and 5% by weight of cysteine with respect to the total amino acids of the keratinous fibres, preferably between 0.1% and 2% by weight.
Non limiting examples of hair keratin reducing agents which can be cited are:
thiols such as thioglycolic acid, thiolactic acid, 3-mercaptopropionic acid, thiomalic acid, 2,3-dimercaptosuccinic acid, cysteine, N-glycyl-L-cysteine, L-cysteinylglycine and their esters and salts, thioglycerol, cysteamine and its C
1
-C
4
acylated derivatives, N-mesylcysteamine, N-acetylcysteine, N-mercaptoalkylamides of sugars such as N-(2-mercaptoethyl)gluconamide, pantetheine, the N-(mercaptoalkyl)-&ohgr;-hydroxyalkylamides described in patent application EPt-A-0 354 835, the N-mono or N,N-dialkyl-4-mercapto butyramides described in patent application EP-A-0 368 763, the aminomercaptoalkylamides described in patent application EP-A-0 432 000, the derivatives of N-mercaptoalkyl)succinamic acid and N-(mercapto-alkyl)succinimides described in patent application EP-A-0 465 342, the alkylamino mercaptoalkylamides described in patent application EP-A-0 514 282, the azeotropic mixture of 2-hydroxypropyl thioglycolate and (2-hydroxy-1-methyl)ethyl thioglycolate described in patent application FR-A-2 679 448, the mercaptoalkylaminoamides described in patent application FR-A-2 692 481, and the N-mercaptoalkyl-alkanediamides described in patent application EP-A-0 653 202;
hydrides such as sodium or potassium borohydride;
alkali or alkaline-earth metal sulphites or bisulphites;
phosphorus derivatives such as phosphines or phosphites;
hyperbranched polymers and dendrimers carrying terminal thiol functions, such as those described in patent application FR 97 04085 and having formula (I):
where:
Y represents an oxygen atom or an NH group;
A represents a linear, branched or cyclic, saturated or unsaturated C
1
-C
12
alkane di-yl group;
this alkane di-yl group can optionally be interrupted by one or more heteroatoms, such as 0 or N;
this alkane di-yl group can optionally be substituted by:
an amino function: —NH
2
, optionally in the form of a salt of a mineral or organic acid;
an acylamino function: —NH—COR, where R represents a linear, branched or cyclic, saturated or unsaturated C
1
-C
10
alkyl group;
a carboxylic acid function;
a C
1
-C
10
ester function;
X represents a nucleophilic group.
In a particular preferred embodiment of the method of the invention, the reducing agent is a phosphine or a salt of a phosphine and a mineral or organic acid.
Among the phosphines which have provided particularly advantageous results as regards the formation of reactive sites on the surface of keratinous hair fibres, mention may be made of those with formula:
where:
R
1
, R
2
and R
3
, which are identical represent:
(a) —(CH
2
)
n
—CH
3
(c) —(CH
2
)
n
—COOR
(d) —(CH
2
)
n
—CONRR′ and
(e) —(CH
2
)
n
—NRR′
n=1 to 3
m=0 or 1 to 3
R and R′, which may be identical or different, represent a hydrogen atom or a linear or branched C
1
-C
4
alkyl radical, and salts of said compounds with formula (II).
Salts of phosphines with formula (II) which can be cited include hydrochlorides, hydrobromides, sulphates, citrates, oxalates and acetates.
Phosphines with general formula (II) which are particularly preferr

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