Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
1999-02-17
2002-04-23
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
C424S070100, C424S070110, C424S070170, C424S070160, C514S880000, C514S881000, C514S846000, C514S937000
Reexamination Certificate
active
06375959
ABSTRACT:
The present application relates to thickening water-in-oil lattices, to a process for their preparation and to their application as thickeners and/or emulsifiers for skincare products and haircare products or for the manufacture of cosmetic, dermo-pharmaceutical or pharmaceutical preparations.
Various thickeners exist and are already used for these purposes. Natural products such as guar gum or corn starch are known in particular, the drawbacks of which are those inherent to natural products, such as price fluctuations, supply difficulties and random quality.
Synthetic polymers in powder form, mainly polyacrylic acids, are also widely used but have the drawback of requiring neutralization when they are used, since they only develop their viscosity from a pH >6.5 and they are often difficult to dissolve.
Synthetic thickening polymers in the form of an inverted latex, that is to say one in which the continuous phase is an oil, are also known. These latlices dissolve extremely quickly; the polymers contained in these inverted lattices are usually acrylamide/alkali metal acrylate copolymers or acrylamide/sodium 2-acrylamido-2-methylpropane-sulphonate copolymers; they are already neutralized and when they are dissolved in water, for example to a concentration of 1%, it is observed that the pH is generally above 6.
However, acrylamide/sodium acrylate copolymers do not develop any appreciable thickening properties when the pH is lowered below 6; on the other hand, the acrylamide/sodium 2-acrylamido-2-methylpropane-sulphonate copolymers described in EP 0,503,853 retain an appreciable thickening capacity even at pH 4.
However, such copolymers have monoacrylamide contents which, although extremely low, could result in making them impossible to use in cosmetics in the near future, following changes in the European legislation on hazardous substances.
The Applicant has thus been concerned with the synthesis and development of polymers that thicken, even at acidic pH, in the form of an inverted latex, without using monoacrylamide.
The subject of the invention is a process for the preparation of a composition comprising an oil phase, an aqueous phase, at least one emulsifier of water-in-oil (W/O) type, at least one emulsifier of oil-in-water (O/W) type, characterized in that the said composition is an inverted latex comprising from 20% to 70% by weight, and preferably from 25% to 45% by weight, of a branched or crosslinked anionic polyelectrolyte based on a monomer possessing a strongly acidic function, characterized in that:
a) an aqueous solution containing the monomers and the optional additives is emulsified in an oil phase in the presence of one or more emulsifiers of water-in-oil type,
b) the polymerization reaction is initiated by introducing a free-radical initiator into the emulsion formed in a), after which the reaction is left to proceed,
c) when the polymerization reaction is complete, one or more emulsifiers of oil-in-water type are introduced at a temperature below 50° C.
The expression “emulsifier of the water-in-oil type” is understood to denote emulsifiers having an HLB value that is low enough to give water-in-oil emulsions, such as the surfactant polymers sold under the name Hypermer™ or such as sorbitan extracts, for instance sorbitan monooleate sold by the company SEPPIC under the tradename Montane 80™, or sorbitan isostearate sold by SEPPIC under the name Montane 70™.
The expression “emulsifier of the oil-in-water type” is understood to denote emulsifiers having an HLB value that is high enough to give oil-in-water emulsions, such as ethoxylated sorbitan esters, for instance sorbitan oleate ethoxylated with 20 mol of ethylene oxide, castor oil ethoxylated with 40 mol of ethylene oxide, sorbitan laurate ethoxylated with 20 mol of ethylene oxide or lauryl alcohol ethoxylated with 7 mol of ethylene oxide.
The term branched polymer is understood to denote a non-linear polymer which has pendant chains so as to obtain, when this polymer is dissolved in water, a high degree of entangling leading to very high low-gradient viscosities.
The term crosslinked polymer is understood to denote a non-linear polymer in the form of a three-dimensional network which is insoluble in water but swellable in water and thus leading to the production of a chemical gel.
The composition prepared by the process according to the invention can contain crosslinked units and/or branched units.
The subject of the invention is, in particular, a process as defined above, characterized in that the polymerization of its precursor monomers is carried out at a pH below 4, and more particularly below or equal to 3.5.
The strongly acidic function of the monomer containing it is, in particular, a sulphonic acid function or a phosphonic acid function, which are partially or totally salified, and the said monomer is preferably chosen from2-methyl-2-[(1-oxo-2-propenyl)amino]-1-propanesulphonic acid which is partially or totally salified in the form of the sodium salt or the ammonium salt.
The subject of the invention is, more particularly, a process as defined above, characterized in that the anionic polyelectrolyte is crosslinked and/or branched with a diethylenic or polyethylenic compound in molar proportion, expressed relative to the monomers used, of from 0.005% to 1% and preferably from 0.01% to 0.1%, and preferably that for which the crosslinking agent and/or the branching agent is chosen from ethylene glycol methacrylate, sodium diallyloxyacetate, diethylene glycol diacrylate, diallylurea, trimethylolpropane triacrylate or methylenebisacrylamide.
The latex according to the invention generally contains from 2.5% to 15% by weight, and preferably from 4% to 9% by weight, of emulsifiers, among which from 20% to 50%, in particular from 25% to 40%, of the total weight of the emulsifiers present are of the water-in-oil (W/O) type and in which from 80% to 50%, in particular from 75% to 60%, of the total weight of the emulsifiers are of the oil-in-water (O/W) type. Such latices also form the subject of the present invention.
According to a specific aspect, the composition as defined above is characterized in that the oil phase represents from 15% to 40%, preferably from 20% to 25%, of its total weight.
This oil phase either consists of a commercial mineral oil containing saturated hydrocarbons such as paraffins, isoparaffins or cycloparaffins, having, at room temperature, a density of between 0.7 and 0.9 and a boiling point above 180° C., such as, for example, Exxol™ D 100 S or Marcol™ 52 sold by Exxon Chemical, isohexadecane or isododecane sold by Bayer, or consists of a plant oil or a synthetic oil or of a mixture of several of these oils.
According to a preferred aspect of the present invention, the oil phase consists of Marcol™ 52 or of isohexadecane; isohexadecane, which is identified in Chemical Abstracts by the number RN=93685-80-4, is a mixture of C
12
, C
16
and C
20
isoparaffins containing at least 97% of C
16
isoparaffins, among which the main constituent is 2,2,4,4,6,8,8-heptamethylnonane (RN=4390-04-9). It is marketed in France by the company Bayer. Marcol™ 52 is a commercial oil corresponding to the definition of liquid petroleum jellies in the French Codex. This is a white mineral oil in accordance with the FDA Regulations 21 CFR 172.878 and CFR 178.3620 (a) and it is listed in the USA Pharmacopoeia, US XXIII (1995) and in the European Pharmacopoeia (1993).
The latices contain between 20% and 50% water. The latices according to the invention can also contain various additives such as complexing agents, transfer agents or chain-limiting agents.
According to another aspect of the present invention, its subject is a process for preparing the composition as defined above, characterized in that:
a) an aqueous solution containing the monomers and the optional additives is emulsified in an oil phase in the presence of one or more emulsifiers of water-in-oil type,
b) the polymerization reaction is initiated by introducing a free-radical initiator into the emulsion formed in a),
Mallo Paul
Tabacchi Guy
Page Thurman K.
Societe d'Exploitation de Produits pour les Industries Chim
Ware Todd D
Young & Thompson
LandOfFree
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