|Title of Invention
COSMETIC COMPOSITIONS COMPRISING A CYCLODIPEPTIDE COMPOUND
|An improved process for the preparation of cosmetic formulations containing a cosmetic active and a continuous phase comprising a water-immiscible liquid carrier, that are structured by a cyclo dipeptide (CDP) having the general formula in which R1 and/or R2, which may be the same or preferably different, each represents a hydrocarbon or alkylene ester group and the other may alternatively represent hydrogen,which employs a monohydric alcohol having a melting point of below 30oC and a boiling point of greater than 100oC and a cosmetic active material optionally together with at least one water-immiscible liquid carrier oil to assist in the dissolution of the structurant and modify the gelling temperature of the resultant mixture. Preferably, the CDP is dissolved in the monohydric alcohol and optionally up to half the water-immiscible oil prior to being mixed with the remaining ingredients of the composition.
THE PATENTS ACT, 1970
(39 of 1970)
The Patents Rules, 2003
(See section 10; rule 13)
1. Title of the invention. - COSMETIC COMPOSITIONS
COMPRISING A CYCLODIPEPTIDE
(a) NAME : HINDUSTAN UNILEVER LIMITED
(b) NATIONALITY : a company incorporated under the Indian Companies Act,
(c) ADDRESS: Hindustan Lever House,
165/166, Backbay Reclamation,
Mumbai - 400 020,
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which
it is to be performed :
Divided out of
Patent Application No. 0373/MUMNP/2004 Nationalisation date 07/07/2004
FIELD OF THE INVENTION
The present invention relates to cosmetic compositions for application to human skin, to the preparation and use of such compositions and to structurants for incorporation in such compositions and their preparation.
BACKGROUND OF THE INVENTION AND SUMMARY OF PRIOR ART
A wide variety of cosmetic compositions for application to human skin make use of a structured liquid carrier to deliver colour or some other active material to the surface of the skin. Significant examples of such cosmetic compositions include antiperspirant or deodorant compositions which are widely used in order to enable their users to avoid or minimise wet patches on their skin, especially in axillary regions or to control or prevent the emission of malodours, which could otherwise arise when the user perspires. Other examples of cosmetic compositions include lip sticks.
Although structuring is a term that has often been employed in respect of materials which structure a carrier liquid, various other terms have been employed alternatively, including thickening, solidifying and gelling.
Antiperspirant or deodorant formulations have been provided with a range of different product forms. One of these is a so-called "stick" which is usually a bar of an apparently
firm solid material held within a dispensing container and which retains its structural integrity and shape whilst being applied. In that respect they are representative of cosmetic compositions in stick form containing other active constituents. When a portion of the stick is drawn across the skin surface, a film of the stick composition is transferred to the skin surface. Although the stick has the appearance of a solid article capable of retaining its own shape for a period of time, the material often has a structured liquid phase so that a film of the composition is readily transferred from the stick to another surface upon contact.
Antiperspirant sticks can be divided into three categories. Suspension sticks contain a particulate antiperspirant active material suspended in a structured carrier liquid phase which often is anhydrous and/or in many instances may be water-immiscible. Emulsion sticks normally have a hydrophilic phase, commonly containing the antiperspirant active in solution, this phase forming an emulsion with a second, more hydrophobic, liquid phase. The continuous phase of the emulsion is structured. Solution sticks typically have the antiperspirant active dissolved in a structured liquid phase which is polar and may comprise a polar organic solvent, which is often water-miscible, and the polar phase can contain water.
There is substantial literature on structuring of cosmetic compositions, for example as represented by antiperspirant or deodorant compositions.
Conventionally, many sticks have been structured using naturally-occurring or synthetic waxy materials, in which term we include materials which resemble beeswax, in that they soften progressively with increase in temperature until they are fluid, generally by about 95°C. Examples of wax-structured sticks are described in an article in Cosmetics and Toiletries, 1990, Vol 105, P75-78, in US patents 5169626 and 4725432 and in many other publications, in some of which such materials are called solidifying agents.
More specifically, it has been common practice for sticks to be structured or solidified by incorporating fatty alcohol into the composition, often accompanied by a smaller amount of castor wax. Sticks which are structured with fatty alcohol tend to leave visible white deposits on application to human skin; moreover the deposits can also transfer onto clothing when it comes into contact with the skin and the wearer can, for example, find white marks at the armhole of the sleeveless garment. Fatty alcohols are often regarded as coming within the general category of waxy materials, but we have observed that they are a more significant source of white deposits than various other waxy materials.
Some alternative structurants or solidifying agents to waxy materials have been proposed. For example, the use of dibenzylidene sorbitol (DBS) or derivatives thereof as gellant for a polar or hydrophylic carrier liquid has been proposed in a number of publications such as EP-A-512770, WO-92/19222, US 4954333, US 4822602 and US 4725430. Cosmetic formulations containing such gellants can suffer from a number of disadvantages, including instability in the
presence of acidic antiperspirants, and comparatively high processing temperatures needed in the production of sticks.
Other alternative proposed structurants include various classes of esters or amides that are solid at ambient temperature and are capable of solidifying a hydrophobic or water-immiscible liquid carrier. One such class comprises ester or amide derivatives of 12-hydroxystearic acid, as described in inter alia US-A-5750096. Another class of such esters or amides comprises N-acyl amino acid amides and esters, of which N-Lauroyl-L-glutamic acid di-n-butylamide is commercially available from Ajinomoto under their designation GP-1. They are described in US patent 3969087. A further class which has been disclosed as gelling agents comprises the amide derivatives of di and tribasic carboxylic acids set forth in WO 98/27954 notably alkyl N,N'-dialkyl succinamides. Yet other amide structurants for water-immiscible liquid carriers are described in EP-A-1305604.
One further class of compounds that have been contemplated as a gelator for cosmetic oils comprises cyclodipeptides. Such compounds contain a -CO-NH- group, and can be considered to be cyclic derivatives of aminoacids.
Various cyclodipeptides has been described in an article by K Hanabusa et al entitled Cyclo(dipeptide)s as low molecular-mass Gelling Agents to harden Organic Fluids, J. Chem Soc. Commun., 1994 ppl40l/2. Various other cyclo(dipeptides) satisfying formula 1 above were described in a second article by Hanabusa et al entitled Low Molecular
Weight Gelators for Organic Fluids: Gelation using a Family of Cyclo (dipeptide) s, in the Journal of Colloid and Interface Science 224, 231-244 (2000). Further cyclodipeptides have been described in Japanese Kokai 10-226615 (1998) or 13-247451 (2001) to Polar Chemical Industries Inc. in which Hanabusa was a named inventor.
In the course of the research leading to the present invention, cyclo dipeptides such as various of those disclosed by Hanabusa were investigated and a sub-class of cyclo dipeptides exhibiting superior gelating properties was identified and described in an as yet unpublished copending application no GB0201164.1 filed in GB on 18/01/2002.
Without being bound to any specific theory or explanation, we believe that, upon structuring of a water-immiscible oil, a network of fibres is formed of the cyclodipeptides that extends throughout the liquid phase, at least increasing the viscosity of the phase and preferably gelling that phase. Upon heating the gel to the gel melting temperature, the strands of structurant dissolve and the liquid phase becomes more mobile. Within the class of compounds identified as cyclodipeptides, the capability of individual members of that class to form a network and the conditions in which a network forms will vary, as will the stability of a network, once formed. However, the class shares the properties outlined below to a greater or lesser extent.
Although cyclo dipeptides can be extremely effective gellants for cosmetic oils, the manufacture of compositions in which they are employed as gellants is subject to a
number of practical constraints or difficulties. First, it is often difficult to incorporate sufficient cyclic dipeptide into the cosmetic oil to enable it to structure or gel the oil to the extent that would be preferred by the manufacturer. That is because the cyclic dipeptides are relatively poorly soluble in commonly employed cosmetic oils, such as volatile or even non-volatile silicone oils. It would be inherently desirable to find a way of increasing the solubility of cyclo dipeptides in the water-immiscible liquid phase of cosmetic formulations.
A further property of cyclic dipeptides relates to the gelling temperature of cosmetic oils containing them. As a generalisation, they tend to gel at higher temperatures than for example waxes or like commonly employed gellants. Furthermore, and unsurprisingly, the gelling temperature of a solution of such a gellant in such oils increases as its concentration in solution increases. The net consequence of its gelation behaviour is that if enough cyclic dipeptide is present to cause the resultant product to have a preferred firmness at ambient temperature, the gelation temperature of the cyclic dipeptide in the oil is undesirably high, commonly in the region of or in excess of 100°C. At such temperatures, many cosmetic oils can evaporate or become discoloured and if the formulation is in the form of an emulsion stick, water evaporation renders the preparation of accurate composition extremely difficult and at worst impossible. Moreover, increased processing temperatures can also result in degradation or discoloration of some cyclic dipeptides themselves. It would be inherently desirable to
find a way of lowering the gelling temperature at which a water-immiscible oil phase occurs to a controllable extent.
The instant inventors accordingly concluded that it would be desirable to identify variations in processing that could ameliorate or overcome the foregoing operational constraints, preferably both at the same time.
SUMMARY OF THE INVENTION
Applicants have now found that the processing of cosmetic formulations employing a cyclodipeptide as a gelling agent for a cosmetic oil carrier can be improved by employing a class of materials that can act as a solvent for the cyclo dipeptides and which is miscible with the cosmetic oils.
It is an object of the present invention to provide structured cosmetic compositions, in which a liquid carrier material is structured using a cyclo dipeptide structurant in the presence of a solvent for the cyclo dipeptide which is miscible with the carrier.
Broadly, in a first aspect of the present invention, there is provided a cosmetic composition comprising:
(i) a cosmetic active material
(ii) a continuous phase which comprises a monohydric alcohol having a melting point of below 3 0°C and a boiling point of greater than 100°C and optionally at least one water-immiscible liquid carrier oil
(ii) a structurant for the continuous phase which comprises a cyclodipeptide having the general formula 1
in which at least one of R1 and R2 which may be the same or different represents an aliphatic group that is optionally substituted by an aromatic or cycloaliphatic group and the other may alternatively represent hydrogen.
Such an monohydric alcohol is miscible with commonly employed or contemplated water-immiscible cosmetic oils and therefore be employed to ameliorate the problems identified above, whilst still retaining the benefits from employing such oils.
By employing a monohydric alcohol having the physical attributes identified above as an essential component of the continuous carrier for the cosmetic active, it is possible to render it easier to obtain structured compositions using the selected structurant, and can also or alternatively enable compositions to be obtained in which the problem of undesirable discoloration can be reduced or eliminated. The incorporation of the selected alcohol can lower the temperature at which the desired concentration of structurant dissolves when the carrier also comprises a water-immiscible oil and can also increase the concentration
of the cyclic dipeptide which can dissolve in the carrier phase, and furthermore can ameliorate or avoid the problem of the mixture becoming immobile at an excessively high temperature.
A solution of the structurant in the cyclo dipeptide compound in the monohydric alcohol or its optional mixture with a water-immiscible oil indicates herein that a separate distinct structurant phase is no longer discernible to the human eye.
A composition of this invention will generally be marketed in a container by means of which it can be applied at time of use. This container may be of conventional type.
A second aspect of the invention therefore provides a cosmetic product comprising a dispensing container having an aperture for delivery of the contents of the container, means for urging the contents of the container through the said aperture, and a composition of the first aspect of the invention in the container.
Means for urging the contents of the container to the said aperture or apertures, for flow through them, may be moving parts operable by the user or an orifice in the container opposite the aperture providing digital access.
According to a third aspect of the present invention there is provided a process for the production of a cosmetic composition comprising the steps of:
a) forming a mixture containing a liquid carrier, a
structurant dissolved therein, and a solid or a disperse liquid phase comprising cosmetic active in particulate or dissolved form at a temperature of at least 40°C and is above the setting temperature of the mixture;
b) introducing the mixture into a mould which preferably is a dispensing container, and
c) cooling or permitting the mixture to cool to ambient temperature,
characterised in that
the structurant is a cyclo dipeptide that satisfies the
general formula 1:-
in which at least one of Ri and R2 which may be the same or different represents an aliphatic group that is optionally substituted by an aromatic or cycloaliphatic group and the other may alternatively represent hydrogen,
and the carrier comprises a monohydric alcohol having a melting point of below 30°C and a boiling point of greater than 10 0°C, a cosmetic active material and optionally at least one water-immiscible liquid carrier oil,
A suspended solid may be any cosmetic active that is at least partly insoluble in a lipophilic water-immiscible
liquid carrier in the amount incorporated therein and a disperse liquid phase may be a solution of such an active in a hydrophilic or polar solvent.
The cyclo dipeptide may conveniently be dissolved in the monohydric alcohol alone or in the presence of only a fraction of any water-immiscible cosmetic oil. Alternatively, all the cosmetic oil can be present at the dissolution stage. The former process variant is particularly desired.
In a fourth aspect of the present invention, the cosmetic active comprises an antiperspirant or deodorant active. Thus, according to the fourth aspect, there is provided a cosmetic method for preventing or reducing perspiration or odour formation on human skin comprising topically applying to the skin a composition comprising a cosmetic active, a water-immiscible liquid carrier and a structurant compound as defined above in the first aspect in which the cosmetic active is an antiperspirant or deodorant active.
DETAILED DESCRIPTION AND EMBODIMENTS
The present invention relates to compositions containing a cosmetic active and a water-immiscible phase that is structured with a cyclodipeptide, to a process for their preparation, to their use and to products containing them. Such compositions and the dispensing package will be described in greater detail, including preferences for individual constituents and combinations thereof and preferred process operations.
Structurant - Cyclo dipeptides
The cyclo dipeptides, sometimes referred to subsequently herein as CDPs, that can be employed in the instant invention can comprise any cyclo dipeptide that satisfies general formula 1 above.
It will recognised that the extent to which a CDP is able to structure a water-immiscible carrier liquid or mixture containing it and the properties of the resultant structured material depend upon many factors, including the CDP itself, the chemical nature of the water-immiscible oil or mixture containing it, and the weight ratio of DPD to the oils. For example, different CDPs have different inherent capabilities to structure oils, often manifesting itself in the range of oils which they can structure and/or the long term physical stability of the resultant structured oil and different oils have different inherent propensity to be structured, often manifesting itself in the range of CDPs that can structure them. An increasing ratio of CDP to carrier oil assists in structuring the oil. Structuring herein indicates the formation of a composition having an increased viscosity compared with a corresponding composition free from CDP, but more desirably the CDP/oils and proportions are chosen together such that the composition is gelled at ambient temperature. A gelled composition does not flow within 24 hours out of a filled container of 2 cm diameter that is lain horizontally at 20°C. It can be assessed more quickly as having gelled by employing the test iii) described hereinafter.
In the CDPs herein, R1 and/or R2 are desirably linked to the cyclodipeptide nucleus through a methylene group -CH2- . Commonly, R1 is different from R2. In many suitable embodiments, one of Ri and R2 (the other being H) or more preferably both Ri and R2 are selected from aliphatic hydrocarbon groups, preferably saturated, which may be linear or branched, optionally terminating in or substituted by an aryl or cycloaliphatic group, and from aliphatic esters of formula - (CH2)n-C02-R3 in which in which n is 0 or preferably an integer of at least 1 and R3 represents an alkyl, cycloalkyl or aryl group. The number of carbons in each of Ri and R2 is often selected in the range of from 1 to 35 and in many instances from 1 to 20.
Examples of suitable alkyl groups for Rx and/or R2 include ethyl, isopropyl, and isobutyl groups. Others which may be contemplated include 2-ethylbutyl, hexyl, 3-methyl-isononyl, and dodecanyl. Examples of suitable aliphatic ester groups for Ri and/or R2 include esters in which n = 0 or 1 or 2, and particularly where n=l. In such or other ester groups, R3 can represents an alkyl group containing at least 2 carbons, particularly up to 2 0 carbons, which may be linear or branched, such as an ethyl, isopropyl, isobutyl, 2-ethylbutyl, hexyl, 3-methyl-isononyl, dodecanyl, hexadecanyl or octadecanyl group.
In a number of preferred embodiments, R3 represents a carbocyclic or heterocyclic group.
In such embodiments, R3 can comprise two fused rings, but preferably comprises a single six membered ring, either
carbocyclic or heterocyclic, or a bridged ring. When R3 is carbocylic, it can be either saturated or unsaturated, preferably mono- or di-unsaturated or aromatic. When R3 is heterocyclic, it is preferably saturated.
R3 is preferably substituted by at least one alkyl substituent, R4, either directly onto the ring or optionally indirectly via an interposed ether or ester linkage. R4 preferably contains no more that 19 carbon atoms, such as one having a longest chain length of up to 4 carbon atoms, and/or a total carbon content of up to 5 carbon atoms. R4 may be linear or branched. Preferred examples include methyl, ethyl, propyl, isopropyl, butyl isobutyl or t-butyl or isopentyl. In a number of very suitable cyclo dipeptides, at least two or more R4 substituents are present, both or all especially desirably being selected from the above list of preferred examples. The R4 substituents may be the same, such as two or more methyl substituents, or may be a combination of different substituents such as a methyl and isopropyl substituents. When R3 is saturated, the R4 substituents may depend from the same carbon atom in the ring, such as two methyl groups, or from different carbon atoms. In several highly desirable cyclic dipeptides, two alkyl R4 substituents are meta or para to each other, for example two methyl groups that are meta to each other or a methyl group and an isopropyl group that are para to each other. In yet other cyclo dipeptides, the ring may include a methylene bridge, which preferably likewise completes a six membered ring.
When R4 is linked to the ring via an ester linkage, the carbonyl carbon in the ester linkage is preferably directly bonded to the ring. In various desirable cyclic dipeptides, R3 satisfies the formula -Ph-CO-0-R4 in which R4 is as described above and particular where R4 comprises 3 to 6 carbons, such as n-butyl.
When RA is heterocyclic, the heterocyclic atom is suitably nitrogen. Conveniently, the heterocyclic atom can be para to the bond with the cyclo dipeptide residue. Moreover, in a number of desirable cyclo dipeptides, the heteroatom is ortho to at least one alkyl group R4, better in a saturated ring and especially to up to 4 ortho R4 groups, that especially are methyl groups.
Examples of such especially preferred R3 group include thymol, isopinocamphenol and 3,5-dialkyl cyclohexanol such as 3,5-dimethyl cyclohexanol.
In several highly desirable embodiments, Ri represents a benzyl group and R2 is an ester of formula (CH2) n-C02-R3 especially those in which n = 1, and R3 represent a carbocylic or heterocyclic group as described above.
Continuous Phase - Carrier oils
Herein, the carrier oils include a monohydric alkanol oil optionally together with at least one water-immiscible carrier cosmetic oil.
The monohydric alkanol for employment in herein can comprise any alkanol which has a melting point that is no higher than 30°C and a boiling point that is greater than 100°C. Preferred alkanols have a melting point that is below 2 5°C and especially below 20°C. Preferably, the alkanols have a boiling point that is greater than 120°C and particularly one that is greater than 150°C. Boiling point and melting point data for alkanols is commonly available, or can be readily determined using standard apparatus. Without being prescriptive, alkanols having a suitable melting point and boiling point can be selected from intermediate chain length linear alkanols, such as butanol through to decanol, eg octanol or decanol; or short cycloalkanols such as cyclopentanol through to cycloheptanol, optionally methyl substituted; intermediate or longer chain length branched alkanols, containing for example from 5 to 24 carbons and especially at least 10 carbons, such as secondary aliphatic alcohols, eg isolauryl alcohol isocetyl alcohol isopalmityl alcohol and isostearyl alcohol or secondary alcohols in which the branch contains from 2 to 10 carbons, such as octyl dodecanol. Still other suitable alcohols can be selected from phenyl-terminated short chain aliphatic alcohols, such a benzyl alcohol and phenylethyl alcohol. Mixtures of such alcohols can be employed, both within the sub-classes of alcohols and between the sub-classes.
It is beneficial to choose monohydric alcohols that themselves are comparatively water-immiscible or at best poorly miscible. In practice, the monohydric alcohols above-identified by name normally satisfy such a preference and such a property is ascertainable from standard reference
works. Any doubt can be resolved by conducting a simple test. In such a test, preferred alcohols are those which are incapable of forming a stable, single phase when mixed gently with de-ionised water (ie in the absence of any solubilising agent or hydrotrope) at 25°C in a weight ratio of 20 parts alcohol to 80 parts water.
The continuous phase carrier liquid system commonly comprises one or a mixture of materials which are relatively hydrophobic so as to be immiscible in water, in addition to the monohydric alcohol.
The weight proportion of the monohydric alcohol in the carrier liquid is at the discretion of the user. Naturally, it will be understood that the beneficial lowering of the gelation temperature and/or the increase in concentration of structurant that can be incorporated increases non-linearly with the proportion of the monohydric alcohol in the carrier. In practice, the choice of weight proportions takes into account many factors, such as the extent to which a particular CDP suffers from the problems in water-immiscible oils described in the introductory section of this text, and/or which sensory or physical properties are more preferred in the eventual product. The proportion of the monohydric alcohol is normally selected in the range of from 5 to 100% of the weight of the carrier oils. In many embodiments, its weight proportion is at least 2 0%. To permit significant variation in the sensory properties of the eventual composition, the weight proportion of the monohydric alcohol conveniently is not more than 70% or 80% of the carrier oils.
The more the monohydric alcohol that is present, the greater the extent to which it can enhance the solubility of the CDP and lower the gelling temperature of the liquid carrier. In many compositions according to the present invention, the selected monohydric alcohol is present in a weight ratio to the CDP of at least 1:1, particularly at least 2:1 and in many practical embodiments is at least 4:1. Although a weight ratio to the CDP of greater than 100:1 can be contemplated, the weight ratio is normally up to 100:1, and in many instances is up to 70:1. In various practical embodiments, the weight ratio to CDP is up to 20:1.
Some hydrophilic liquid may be included in the carrier, provided the overall carrier liquid mixture is immiscible with water. It will generally be desired that this carrier is liquid (in the absence of structurant) at temperatures of 15°C and above. It may have some volatility but its vapour pressure will generally be less than 4kPa (30 mmHg) at 25°C so that the material can be referred to as an oil or mixture of oils. More specifically, it is desirable that at least 80% by weight of the hydrophobic carrier liquid should consist of materials with a vapour pressure not over this value of 4kPa at 25°C.
It is preferred that the hydrophobic carrier material includes a volatile liquid silicone, i.e. liquid polyorganosiloxane. To class as "volatile" such material should have a measurable vapour pressure at 20 or 25°C. Typically the vapour pressure of a volatile silicone lies in a range from 1 or 10 Pa to 2 kPa at 25°C.
It is desirable to include volatile silicone because it gives a "drier" feel to the applied film after the composition is applied to skin.
Volatile polyorganosiloxanes can be linear or cyclic or mixtures thereof. Preferred cyclic siloxanes include polydimethylsiloxanes and particularly those containing from 3 to 9 silicon atoms and preferably not more than 7 silicon atoms and most preferably from 4 to 6 silicon atoms, otherwise often referred to as cyclomethicones. Preferred linear siloxanes include polydimethylsiloxanes containing from 3 to 9 silicon atoms. The volatile siloxanes normally by themselves exhibit viscosities of below 10"5 m2/sec (10 centistokes), and particularly above 10"7 m2/sec (0.1 centistokes), the linear siloxanes normally exhibiting a viscosity of below 5 x 10'6 m2/sec (5 centistokes) . The volatile silicones can also comprise branched linear or cyclic siloxanes such as the aforementioned linear or cyclic siloxanes substituted by one or more pendant -0-Si(CH3)3 groups. Examples of commercially available silicone oils include oils having grade designations 344, 345, 244, 245 and 246 from Dow Coming Corporation; Silicone 7207 and Silicone 7158 from Union Carbide Corporation; and SF1202 from General Electric.
The hydrophobic carrier employed in compositions herein can alternatively or additionally comprise non-volatile silicone oils, which include polyalkyl siloxanes, polyalkylaryl siloxanes and polyethersiloxane copolymers. These can suitably be selected from dimethicone and dimethicone copolyols. Commercially available non-volatile silicone
oils include products available under the trademarks Dow Corning 556 and Dow Corning 200 series. Other non volatile silicone oils include that bearing the trademark DC704. Incorporation of at least some non-volatile silicone oil having a high refractive index such as of above 1.5, eg at least 10% by weight (preferably at least 25% to 100% and particularly from 40 to 80%) of the silicone oils is often beneficial in some compositions, because this renders it easier to match the refractive index of the constituents of the composition and thereby easier to produce transparent or translucent formulations.
The water-immiscible oil employed in the carrier in addition to the monohydric alcohol may comprise from 0% to 100% by weight of one or more liquid silicones. In some embodiments, there is sufficient liquid silicone to provide at least 10%, better at least 15%, by weight of the whole composition. When silicone oil is used in various embodiments, for example in emulsions, volatile silicone preferably constitutes from 20 to 100% of the weight of the carrier liquid. In a number of embodiments, when a non-volatile silicone oil is present, its weight ratio to volatile silicone oil is chosen in the range of from 5:1 to 1:50.
Silicon-free hydrophobic oils can be used instead of, or more preferably in addition to liquid silicones. Silicon-free hydrophobic organic oils that can be incorporated include liquid aliphatic hydrocarbons such as mineral oils or hydrogenated polyisobutene, often selected to exhibit a low viscosity. Further examples of liquid hydrocarbons are
polydecene and paraffins and isoparaffins of at least 10 carbon atoms.
Other suitable hydrophobic carriers comprise liquid aliphatic or aromatic esters. Suitable aliphatic esters contain at least one long chain alkyl group, such as esters derived from Ci to C2o alkanols esterified with a C8 to C22 alkanoic acid or C6 to Ci0 alkanedioic acid. The alkanol and acid moieties or mixtures thereof are preferably selected such that they each have a melting point of below 20°C. These esters include isopropyl myristate, lauryl myristate, isopropyl palmitate, di-isopropyl sebacate and di-isopropyl adipate.
Suitable liquid aromatic esters, preferably having a melting point of below 20°C, include fatty alkyl benzoates. Examples of such esters include suitable C8 to Ci8 alkyl benzoates or mixtures thereof, including in particular C12 to C15 alkyl benzoates eg those available under the trademark Finsolv. Other suitable aromatic esters include alkyl naphthalates, alkyl salicylates and aryl benzoates of MP Further instances of suitable hydrophobic carriers comprise liquid aliphatic ethers derived from at least one fatty alcohol, such as myristyl ether derivatives e.g. PPG-3
myristyl ether or lower alkyl ethers of polygylcols such as an ether having named as PPG-14 butyl ether by the CTFA.
Aliphatic alcohols which are liquid at 2 0°C and boil at above 100°C provide an essential constituent of the instant invention formulations, and especially desirably those which are clearly water-immiscible. Such alcohols can often constitute from 10% or 15% to 30% or 55% by weight of the cosmetic composition.
Silicon-free liquids can constitute from 0-100% of the residue of the water-immiscible liquid carrier, i.e. other than said above-mentioned essential aliphatic alcohols, but it is preferred that silicone oil is present and that the amount of silicon-free constituents preferably constitutes up to 50 or 60% and in many instances from 10 to 60% by weight, eg 15 to 30% or 30 to 50% by weight, of the water-immiscible carrier liquid.
As will be explained in more detail below, in cosmetic compositions herein, the structured water-immiscible carrier liquid may be the continuous phase in the presence of a dispersed second phase, which may comprise a suspension of particulate solid forming a suspension stick or a dispersion of droplets of a lypohobic liquid. Such a solid may be a particulate antiperspirant or deodorant active or pigment. Such a disperse liquid phase may comprise a solution of the aforementioned active or actives in water or other hydrophilic ie lypophobic solvent.
As mentioned hereinabove, in accordance with the first aspect, the invention requires a CDP structurant to structure a carrier oil that comprises a monohydric alcohol. A cosmetic active is present in cosmetic compositions and other materials may also be present depending on the nature of the composition. The various materials will now be discussed by turn and some preferred features and possibilities will be indicated.
The proportion of the CDP structurant in a composition of this invention is likely to be from 0.1 to 15% by weight of the whole composition and preferably from 0.1 up to 10%. Its weight proportion more commonly is at least 0.3% and in many instances not more than 5%. In some especially desirable embodiments, the amount of CDP structurant is from 0.5% to 3.5% or 5%. It will be recognised that for any particular CDP, its maximum proportion in the composition will vary in accordance with its solubility in the selected monohydric alcohol and the conditions prevailing during the dissolution process, such as temperature. Herein, unless other wise stated, a % for the CDP is by weight based on the entire composition.
If the composition is an emulsion with a separate disperse phase, the amount of structurant compound(s) is likely to be from 0.3 to 20% by weight of the continuous phase, more likely from 0.6% to 8% of this phase. In some highly desirable embodiments the hydrophobic carrier continuous phase contains from 2 to 5% by weight of the CDP.
Liquid Disperse Phase in emulsions
If the composition is an emulsion in which the cyclo dipeptide acts as a structurant in the hydrophobic continuous phase, the emulsion will contain a more polar or lypophobic disperse phase. The disperse phase may be a solution of an active ingredient.
The hydrophilic disperse phase in an emulsion commonly comprises water as solvent and can comprise one or more water soluble or water miscible liquids in addition to or in replacement of water. The proportion of water in an emulsion according to the present invention is often selected in the range of up to 60%, and particularly from 10% up to 40% or 50% of the whole formulation.
One class of water soluble or water-miscible liquids comprises short chain monohydric alcohols, e.g. Ci to C4 and especially ethanol or isopropanol, which can impart a deodorising capability to the formulation. Ethanol gives a cooling effect on application to skin, because it is very volatile. It is preferred that the content of ethanol or any other monohydric alcohol with a vapour pressure above 1.3kPa (10 mmHg) is not over 15% better not over 8% by weight of the composition.
A further class of hydrophilic liquids comprises diols or polyols preferably having a melting point of below 40°C, or which are water miscible. Examples of water-soluble or water-miscible liquids with at least one free hydroxy group include ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, hexylene glycol, diethylene glycol, dipropylene glycol, 2-ethoxyethanol, diethylene glycol monomethylether, triethyleneglycol monomethylether and sorbitol. Especially preferred are propylene glycol and glycerol.
In an emulsion the disperse phase is likely to constitute from 5 to 8 0 or 85% of the weight of the composition preferably from 5 to 50 or 65% more preferably from 25 or 35% up to 50 or 65%, while the continuous phase with the structurant therein provides the balance from 15 or 35% up to 95% of the weight of the composition. Compositions with high proportion of disperse phase, i.e. from 65 to 85% disperse phase, may be advantageous because they can give good hardness even though the concentration of structurant may be only a small percentage of the total composition. However, compositions with a lower proportion of disperse phase can also be advantageous because they tend to offer a drier and warmer feel.
An emulsion composition will generally include one or more emulsifying surfactants which may be anionic, cationic, zwitterionic and/or nonionic surfactants. The proportion of emulsifier in the composition is often selected in the range up to 10% by weight and in many instances from 0.1 or 0.25 up to 5% by weight of the composition. Most preferred is an amount from 0.1 or 0.25 up to 3% by weight. Nonionic
emulsifiers are frequently classified by HLB value. It is desirable to use an emulsifier or a mixture of emulsifiers with an overall HLB value in a range from 2 to 10 preferably from 3 to 8.
It may be convenient to use a combination of two or more emulsifiers which have different HLB values above and below the desired value. By employing the two emulsifiers together in appropriate ratio, it is readily feasible to attain a weighted average HLB value that promotes the formation of an emulsion.
Many suitable emulsifiers of high HLB are nonionic ester or ether emulsifiers comprising a polyoxyalkylene moiety, especially a polyoxyethylene moiety, often containing from about 2 to 80, and especially 5 to 60 oxyethylene units, and/or contain a polyhydroxy compound such as glycerol or sorbitol or other alditol as hydrophilic moiety. The hydrophilic moiety can contain polyoxypropylene. The emulsifiers additionally contain a hydrophobic alkyl, alkenyl or aralkyl moiety, normally containing from about 8 to 50 carbons and particularly from 10 to 30 carbons. The hydrophobic moiety can be either linear or branched and is often saturated, though it can be unsaturated, and is optionally fluorinated. The hydrophobic moiety can comprise a mixture of chain lengths, for example those deriving from tallow, lard, palm oil, sunflower seed oil or soya bean oil. Such nonionic surfactants can also be derived from a polyhydroxy compound such as glycerol or sorbitol or other alditols. Examples of emulsifiers include ceteareth-10 to -25, ceteth-10-25, steareth-10-25 (i.e. C16 to C18 alcohols
ethoxylated with 10 to 25 ethylene oxide residues) and PEG-15-25 stearate or distearate. Other suitable examples include C10-C20 fatty acid mono, di or tri-glycerides. Further examples include C18-C22 fatty alcohol ethers of polyethylene oxides (8 to 12 EO).
Examples of emulsifiers, which typically have a low HLB value, often a value from 2 to 6 are fatty acid mono or possibly diesters of polyhydric alcohols such as glycerol, sorbitol, erythritol or trimethylolpropane. The fatty acyl moiety is often from C14 to C22 and is saturated in many instances, including cetyl, stearyl, arachidyl and behenyl. Examples include monoglycerides of palmitic or stearic acid, sorbitol mono or diesters of myristic, palmitic or stearic acid, and trimethylolpropane monoesters of stearic acid.
A particularly desirable class of emulsifiers comprises dimethicone copolymers, namely polyoxyalkylene modified dimethylpolysiloxanes. The polyoxyalkylene group is often a polyoxyethylene (POE) or polyoxypropylene (POP) or a copolymer of POE and POP. The copolymers often terminate in C1 to C12 alkyl groups.
Suitable emulsifiers and co-emulsifiers are widely available under many trade names and designations including Abil™, Arlacel™, Brij™, Cremophor™, Dehydrol™, Dehymuls™, Emerest™, Lameform™, Pluronic™, Prisorine™, Quest PGPH™, Span™, Tween™, SF1228, DC3225C and Q2-5200.
The cosmetic actives employable herein can comprise antiperspirant or deodorant actives or pigments.
The composition preferably contains an antiperspirant active. Antiperspirant actives, are preferably incorporated in an amount of from 0.5-60%, particularly from 5 to 3 0% or 40% and especially from 5 or 10% to 30 or 35% of the weight of the composition.
Antiperspirant actives for use herein are often selected from astringent active salts, including in particular aluminium, zirconium and mixed aluminium/zirconium salts, including both inorganic salts, salts with organic anions and complexes. Preferred astringent salts include aluminium, zirconium and aluminium/zirconium halides and halohydrate salts, such as chlorohydrates and activated aluminium chlorohydrates.
Aluminium halohydrates are usually defined by the general formula Al2 (OH)xQy.wH20 in which Q represents chlorine, bromine or iodine, x is variable from 2 to 5 and x + y = 6 while wH20 represents a variable amount of hydration. Especially effective aluminium halohydrate salts, known as activated aluminium chlorohydrates, are described in EP-A-6739 (Unilever NV et al), the contents of which specification is incorporated herein by reference. Some activated salts do not retain their enhanced activity in the presence of water but are useful in substantially anhydrous
formulations, i.e. formulations which do not contain a distinct aqueous phase.
Zirconium actives can usually be represented by the empirical general formula: ZrO (OH) 2n.nzBz.wH20 in which z is a variable in the range of from 0.9 to 2.0 so that the value 2n-nz is zero or positive, n is the valency of B, and B is selected from the group consisting of chloride, other halide, sulphamate, sulphate and mixtures thereof. Possible hydration to a variable extent is represented by wH20. Preferable is that B represents chloride and the variable z lies in the range from 1.5 to 1.87. In practice, such zirconium salts are usually not employed by themselves, but as a component of a combined aluminium and zirconium-based antiperspirant.
The above aluminium and zirconium salts may have coordinated and/or bound water in various quantities and/or may be present as polymeric species, mixtures or complexes. In particular, zirconium hydroxy salts often represent a range of salts having various amounts of the hydroxy group. Zirconium aluminium chlorohydrate may be particularly preferred.
Antiperspirant complexes based on the above-mentioned astringent aluminium and/or zirconium salts can be employed. The complex often employs a compound with a carboxylate group, and advantageously this is an amino acid. Examples of suitable amino acids include dl-tryptophan, dl-|3-phenylalanine, dl-valine, dl-methionine and iS-alanine, and preferably glycine which has the formula CH2(NH2)COOH.
It is highly desirable to employ complexes of a combination of aluminium halohydrates and zirconium chlorohydrates together with amino acids such as glycine, which are disclosed in US-A-3792068 (Luedders et al). Certain of those Al/Zr complexes are commonly called ZAG in the literature. ZAG actives generally contain aluminium, zirconium and chloride with an Al/Zr ratio in a range from 2 to 10, especially 2 to 6, an Al/Cl ratio from 2.1 to 0.9 and a variable amount of glycine. Actives of this preferred type are available from Westwood, from Summit and from Reheis.
Other actives which may be utilised include astringent titanium salts, for example those described in GB 2299506A.
The proportion of solid antiperspirant salt in a suspension composition normally includes the weight of any water of hydration and any complexing agent that may also be present in the solid active. However, when the active salt is incorporated in solution in a hydrophilic solvent such as a glycol, its weight commonly excludes any water present.
If the composition is in the form of an emulsion the antiperspirant active will be dissolved in the disperse phase. In this case, the antiperspirant active will often provide from 3 to 60% by weight of the disperse phase, particularly from 10% or 20% up to 55% or 60% of that phase. Alternatively, the composition may take the form of a suspension in which antiperspirant active in particulate form is suspended in the water-immiscible liquid carrier. Such a composition will probably not have any separate
aqueous phase present and may conveniently be referred to as "substantially anhydrous" although it should be understood that some water may be present bound to the antiperspirant active or as a small amount of solute within the water-immiscible liquid phase. In such compositions, the particle size of the antiperspirant salts often falls within the range of 0.1 to 200 mm with a mean particle size often from 3 to 20/^m. Both larger and smaller mean particle sizes can also be contemplated such as from 20 to 50^m or 0.1 to 3/xm.
Suitable deodorant actives can comprise deodorant effective concentrations of antiperspirant metal salts, deoperfumes, and/or microbicides, including particularly bactericides, such as chlorinated aromatics, including biguanide derivatives, of which materials known as Igasan DP300™ (triclosan) , Tricloban™, and Chlorhexidine warrant specific mention. A yet another class comprises biguanide salts such as are available under the trade mark Cosmosil™. Deodorant actives are commonly employed at a concentration of from 0.1 to 25% by weight.
Other optional ingredients include wash-off agents, often present in an amount of up to 10% w/w to assist in the removal of the formulation from skin or clothing. Such wash-off agents are typically nonionic surfactants such as esters or ethers containing a C8 to C22 alkyl moiety and a hydrophilic moiety which can comprise a polyoxyalkylene group (POE or POP) and/or a polyol.
A further optional constituent of the formulation comprises one or more further structurants which can be employed in addition to the cyclo dipeptide. Herein, the CDP may be the primary structurant, by which is meant that is employed at a concentration that is higher than that of the further structurant. However, in some advantageous embodiments, the further structurant may be present in an amount that is at least that of the CDP. In such advantageous embodiments, the CDP is acting to moderate the properties of the further structurant such that the properties using the combined structurant system are superior in at least one desirable respect to using the further structurant alone. The amount of such further structurants in the formulation is often from zero to not more than 15% of the formulation. In some instances, the further structurant is present in a weight ratio to the CDP of from 10:1 to 1:10.
The further structurants employable herein can be non-polymeric or polymeric. Solid linear fatty alcohol and/or a wax may be included but are not preferred. In anhydrous compositions notably antiperspirants which are suspension sticks, non-polymeric further structurants, sometimes referred to as gellants, can be selected from fatty acids or salts thereof, such as stearic acid or sodium stearate or 12-hydroxy stearic acid. Linear fatty acids are preferably not used in aqueous sticks, e.g. aqueous emulsion sticks because they can form insoluble precipitates with aluminium ions. Other suitable gellants can comprise dibenzylidene alditols, e.g. dibenzylidene sorbitol. Further suitable gellants can comprise selected N-acyl amino acid derivatives, including ester and amide derivatives, such as
N-lauroyl glutamic acid dibutylamide, which gellants can be contemplated in conjunction with 12-hydroxy stearic acid or an ester or amide derivative thereof. Still further gellants include amide derivatives of di or tribasic carboxylic acids, such as alkyl N,N' dialkylsuccinamides, e.g. dodecyl N,N'-dibutylsuccinamide. When employing further structurants comprising N-acyl amino acid derivatives, in some highly desirably formulations their weight ratio to CDP is selected in the range of 1:1 to 6:1.
Polymeric structurants which can be employed as further structurants can comprise organo polysiloxane elastomers such as reaction products of a vinyl terminated polysiloxane and a cross linking agent or alkyl or alkyl polyoxyalkylexterminated poly (methyl substituted) or poly (phenyl substituted) siloxanes. A number of polyamides have also been disclosed as structurants for hydrophobic liquids. Polymers containing both siloxane and hydrogen bonding groups, which might be used as secondary structurants, have been disclosed in WO 97/36572 and WO 99/06473. If an aqueous disperse phase is present, polyacrylamides, polyacrylates or polyalkylene oxides may be used to structure or thicken this aqueous phase.
It is highly desirable that any further structurant employed herein is itself fibre-forming, that is to say forms a fibrous structure within the hydrophobic phase. Most preferably the fibre-forming structurant is one in which the fibrous structure is not visible to the human eye.
Fatty alcohols which are solid at room temperature of 20°C, such as linear monohydric alkanols containing at least 12 carbons e.g. stearyl alcohol or behenyl alcohol, lead to deposits with an opaque white appearance and are preferably substantially absent, by which we mean present in an amount of no more than 3% by weight of the composition, more preferably less than 1% and most preferably are not incorporated specifically, ie 0%. As already mentioned, fatty alcohols are often regarded as coming within the general category of waxy materials. More generally the term "wax" is conventionally applied to a variety of materials and mixtures (including some fatty alcohols) which have some diversity in chemical structure but similarity in physical properties. The term generally denotes materials which are solid at 30°C, often also solid up to 40°C, having a waxy appearance or feel, but which gradually soften and eventually melt to a mobile liquid at a temperature below 95°C usually below 90°C.
Possibly the composition does not include more than 3% of any material which is a wax, ie a solid at 3 0°C but softens at an elevated temperature and at 95°C is molten and soluble in the water-immiscible liquid, yet which is unable to form a network of fibres therein on cooling to 20°C.
The compositions herein can incorporate one or more cosmetic adjuncts in amounts conventionally contemplatable for cosmetic solids or soft solids. Such cosmetic adjuncts can include skin feel improvers, such as small particle inorganic mineral substances like talc, finely divided silica and/or bentonite or similar clays, or finely divided
polyethylene, for example in an amount of up to about 10%; skin benefit agents such as allantoin or lipids, for example in an amount of up to 5%; colours; skin cooling agents other than the already mentioned alcohols, such a menthol and menthol derivatives, often in an amount of up to 2%, all of these percentages being by weight of the composition. A commonly employed adjunct is a perfume, which is normally present at a concentration of from 0 to 4% and in many formulations from 0.25 to 2% by weight of the composition.
The sticks produced employing the CDP structurants can be either opaque or translucent or even transparent, depending at least partly on the extent to which the refractive indices (RI) of the appropriate ingredients are matched. Translucent or transparent formulations are possible in respect of the invention formulations because the CDP structurant forms a fibrous structure within the liquid hydrophobic carrier that is not seen by the human eye. By matched herein is meant that the difference between the refractive indices is less than 0.005 and preferably less than 0.002. In suspension sticks, to achieve at least translucency without using exclusively sub-micron sized particles, it is necessary to match the RI of the suspended cosmetic active, eg the particulate antiperspirant salt, with the RI of the suspending carrier oil mixture. This can be assisted by a suitable choice of oils, and in particular mixtures containing those having an RI of above 1.46, such as from 1.46 to 1.56. In regard to the suspended particulates, RI matching can be assisted by controlling the particle size distribution, and particularly by not
permitting an excess proportion of 1 to 10 micron particles and advantageously by avoiding the manufacture of hollow sphere antiperspirant actives or subsequently removing the hollows. Matching can be further assisted by modifying the RI of the suspended cosmetic active, such as an aluminium-containing antiperspirant active by post treating it with water (re-hydration) or by retaining a comparatively high water content during the manufacture process. In emulsion formulations, the relevant ingredients to RI match comprise the disperse and continuous liquid phases.
It is highly desirable to employ RI matching as indicated above in conjunction with the exclusion, to the extent necessary, of additional suspended materials having a different refractive index from the suspending medium, such as for example a suspended filler or additional cosmetic active, to enable the resultant composition to transmit at least 1% light (in the test described hereinafter).
Mechanical Properties and Product Packages
The compositions of this invention are structured liquids and are firm in appearance. A composition of this invention will usually be marketed as a product comprising a container with a quantity of the composition therein, where the container has an aperture for the delivery of composition, and means for urging the composition in the container towards the delivery aperture. Conventional containers take the form of a barrel of oval cross section with the delivery aperture at one end of the barrel.
A composition of this invention may be sufficiently rigid that it is not apparently deformable by hand pressure and is suitable for use as a stick product in which a quantity of the composition in the form of a stick is accommodated within a container barrel having an open end at which an end portion of the stick of composition is exposed for use. The opposite end of the barrel is often closed.
Generally the container will include a cap for its open end and a component part which is sometimes referred to as an elevator or piston fitting within the barrel and capable of relative axial movement along it. The stick of composition is accommodated in the barrel between the piston and the open end of the barrel. The piston is used to urge the stick of composition along the barrel. The piston and stick of composition may be moved axially along the barrel by manual pressure on the underside of the piston using a finger or rod inserted within the barrel. Another possibility is that a rod attached to the piston projects through a slot or slots in the barrel and is used to move the piston and stick. Preferably the container also includes a transport mechanism for moving the piston comprising a threaded rod which extends axially into the stick through a correspondingly threaded aperture in the piston, and means mounted on the barrel for rotating the rod. Conveniently the rod is rotated by means of a hand-wheel mounted on the barrel at its closed end, i.e. the opposite end to the delivery opening.
The component parts of such containers are often made from thermoplastic materials, for example polypropylene or
polyethylene. Descriptions of suitable containers, some of which include further features, are found in US patents 4865231, 5000356 and 5573341.
Compositions of this invention can be produced by process similar to conventional processes for making cosmetic solids. Such processes involve forming a heated mixture of the structurant in the carrier oil, in this case the monohydric alcohol and optionally together with a fraction or even all of any other oil, at a temperature which is sufficiently elevated that all the structurant dissolves, pouring that mixture into a mould, which may take the form of a dispensing container, and then cooling the mixture whereupon the structurant solidifies into a network of fibres extending through the water-immiscible liquid phase. The employment of the monohydric alcohol in the continuous carrier enables the benefits of higher CDP concentration and reduced gelling temperature to be attained
A convenient process sequence for a composition which is a suspension comprises first forming a solution of the structurant in the monohydric alcohol and optionally a fraction of or even all the water-immiscible liquids. This is normally carried out by agitating the mixture at a temperature sufficiently high that all the structurant dissolves (the dissolution temperature) such as a temperature in a range from 50 to 140°C. Thereafter, the particulate constituent, for example particulate antiperspirant active, is blended with the hot mixture. This may be done slowly, and/or the particulate solid
preheated, in order to avoid premature gelation. The resulting blend is then introduced into a dispensing container such as a stick barrel. This is usually carried out at a temperature 5 to 30°C above the setting (gelling) temperature of the composition. The container and contents are then cooled to ambient temperature. Cooling may be brought about by nothing more than allowing the container and contents to cool. Cooling may be assisted by blowing ambient or even refrigerated air over the containers and their contents.
In a suitable procedure for making emulsion formulations, a solution of the structurant in the continuous carrier phase is prepared at an elevated temperature just as for suspension sticks. If any emulsifier is being used, this is conveniently mixed into this liquid phase. Separately, an aqueous or hydrophilic disperse phase is prepared by introduction of antiperspirant active into the liquid part of that phase (if this is necessary: antiperspirant actives can sometime be supplied in aqueous solution which can be utilised as is). If possible, this solution of antiperspirant active which will become the disperse phase is preferably heated to a temperature similar to that of the continuous phase with structurant therein, but without exceeding the boiling point of the solution, and then mixed with the continuous phase. Alternatively, the solution is introduced at a rate which maintains the temperature of the mixture. If it is necessary to work at a temperature above the boiling temperature of the disperse phase, or at a temperature where evaporation from this phase is significant, a pressurised apparatus could be used to allow
a higher temperature to be reached. After the two phases are mixed, the resulting mixture is filled into dispensing containers, typically at a temperature 5 to 3 0°C above the setting temperature of the composition, and allowed to cool as described above for suspension sticks.
Many of the cosmetic compositions according to the present invention employ a mixture of at least one hydrophobic cosmetic oil (carrier fluid) with the monohydric alcohol. In some convenient preparative routes, it is desirable to dissolve the CDP structurant in the alcohol, optionally in conjunction with a minor proportion of an alcohol having some water-miscibility and boiling point above the dissolution temperature of CDP in the alcoholic fluid. This enables the remainder of the carrier fluids to avoid being taken to the temperature at which the CDP dissolves or melts. The proportion of the carrier fluids for dissolving the CDP is often from 15 to 85% by weight of the carrier fluids, and particularly from 20 to 40% or 70%. In one variation, the CDP structurant is first dissolved by heating to an elevated temperature with stirring in a mixture comprising the monohydric alcohol plus up to a quarter or even up to half of the total of any water-immiscible cosmetic oil employed in the composition, and there after mixing the solution of the CDP with the remainder of the cosmetic oil and the cosmetic active, such a particulate antiperspirant or an aqueous solution of an antiperspirant. The remainder of the cosmetic oil and of the cosmetic active are taken to a suitable temperature such that the temperature of their mixture with the CDP solution is still above the gelling temperature of the composition, preferably
no more than 5 or 10°C above the gelling temperature, which may have been determined in a previous trial.
CDP structurants can be made by one or more of the general preparative routes published in the above-identified papers by Hanabusa with appropriately chosen reagents to obtain the desired substituent groups Ri and R2 of the cyclo dipeptide, and/or by variations described hereinbelow or the general method described herein to make the materials CDP1 to CDP13.
One route of general applicability described by Hanabusa comprises the cyclisation of dipeptide ethyl esters under reflux in 1,3,5-trimethyl benzene, the esters being obtained by catalytic hydrogenation of the corresponding N-benzoylcarbonyl dipeptide ethyl ether with 10% Pd-C. In a variation thereof, ester groups in an existing ester CDP can be replaced in a conventional transesterification process in the corresponding alcohol, eg 3,7-dimethyloctanola.
Various of the CDPs are derivable indirectly from aspartame by esterifying cyclo[(R)-phenylalany1] that is obtainable by heating aspartame, preferably in the presence of a substantial excess of a low molecular weight aliphatic alcohol, such as isopropanol, under reflux for a long period. Desirably, the alcohol is employed in a weight ratio to aspartame of greater than 50:1 such as up to 100:1, and the reaction is continued for at least 10 hours at reflux temperature, such as from 15 to 24 hours. During the reaction, the aspartame gradually dissolves. On cooling, the resultant solution yields a white powder. Removal of
the solvent from the filtrate yields a solid which, after washing with acetone, provides a further amount of the white product, confirmed by a combined yield of the CDP precursor acid of 79 %.
The precursor acid can be reacted with the relevant alcohol of formula RAOH, preferably in a mole ratio to the precursor of at least 1:1 to 10:1, particularly from 1.5:1 to 7:1 and especially at least 2:1 in dimethyl sulphoxide, conveniently in a ratio of at least 4:1 (vol-.wt), preferably from 6:1 to 12:1, and preferably in the presence of a promoter, such as a carbonyldiimidazole, in an amount preferably from 0.5 to 2 moles of promoter per mole of precursor acid. The reaction is conveniently carried out at a mildly elevated temperature, such as up to 60°C and particularly from 4 0 to 60°C for a period of at least 6 hours and preferably from 9 to 24 hours. The resultant solution is quenched in excess ambient or cooler water, desirably after the solution has cooled to ambient, a solid precipitates and is filtered off, water washed until no residual diimidazole remained and then can be purified by washing with diethyl ether or toluene, and dried.
Preparation of CDP Structurants
The cyclo dipeptide structurants employed in the following Examples and Comparisons were made by the following general method employing (2S-cis)-(-)-5-benzyl-3,6-dioxo-2-piperazine acetic acid (DOPAA) which was reacted with the alcohols specified in Table 1 below.
A 250 ml 3 necked round bottomed flask equipped with a stirrer was charged with (2S-cis)-(-)-5-benzyl-3,6-dioxo-2-piperazine acetic acid (DOPAA) (18.4 mmol), and dimethyl sulfoxide (8mls per lg of DOPAA) was then introduced at laboratory ambient temperature (about 22°C) with stirring. The DOPAA dissolved only partially. 1,1'-carbonyldiimidazole (22 mmol) was then introduced with stirring in the amount specified in the Table. Vigorous effervescence occurred and the react mixture was left stirring at room temperature for 45 minutes after which time the reaction mixture went clear. The specified alcohol (92 mmol) was stirred into the clear reaction mixture and maintained at 50°C overnight (between 16 and 2 0 hours), whereupon it was allowed to cool to ambient temperature (about 22°C) , and poured into water, producing a precipitate which was filtered off and washed with further quantities of water until any residual diimidazole had been removed (as shown by ^nmr) . The washed precipitate was then washed with diethyl ether. The washed product was dried in a vacuum oven to constant weight and its melting point determined, the results quoted herein being obtained by DSC with a heating rate of 10°C/min, except for those marked ET, which
were obtained using a an Electrothermal 9109 digital melting point measuring apparatus.
CDP Alcohol Purity % Melting Point °C
CDP1 (1S,2R,5S)-(+) Menthol 98.7 238
CDP2 Thymol 99.3 212
CDP 3 1R,2R,3R,5S-(-)-iso-pinocamphenol 68 >200
CDP4 3,5-dimethyl-cyclohexanol 94 212
CDP5 phenol 99.7 246
CDP 6 butyl-4-hydroxy benzoate 98.5 217
CDP7 iso-propanol 98.5 215
CDP8 n-propanol 98.2 200
CDP 9 4-t-butylphenol 99.1 237
CDP10 carveol 65.0 215ET
CDP11 carvacrol 99.1 229ET
CDP 12 5,6,7,8-tetrahydronaphth-2-ol 99.3 220ET
CDP 13 2 -isopropoxyphenol 98.8 178ET
The materials used in gel studies or the preparation of cosmetic formulations, and their proprietary names, other than the structurants CDP1 to CDP9, are summarised in Table 2:
Abrev CFTA name Trade Name/supplier
1 ISA Isostearyl Alcohol Pricerine 3 515 ™ - Uniqema
2 ODA Octyl Dodecanol Eutanol G ™ - Cognis
3 BMA Benzyl Alcohol Acros
4 8MA octyl Alcohol Sigma
5 10MA decyl Alcohol Sigma
6 ICA iso-cetyl Alcohol Eutanol G16 - Cognis
7 TN C12-15 alkyl benzoate Finsolv TN ™ from Finetex Inc
8 245 Cyclomethicone DC 245 ™ - Dow Corning Inc
9 364 Hydogenated Polydecene Silkflo 3 64 NF ™- Albemarle
10 704 1,1,5,5-tetraphenyl trisiloxane DC704™: Dow Corning Inc
11 GP1 N-lauroyl-L-glutamic acid Di-n-butylamide GP-l™Ajinomoto Co Inc
18 DBS dibenzylidene sorbitol Roquette
19 HSA 12- hydroxystearic acid 12-HSA (CasChem)
20 930 Polyamide Versamid 930™ (Cognis)
12 EM90 Dimethicone Copolyol Abil EM90™ -Th. Goldschmidt AG
21 P135 dipolyhydroxy-stearate Arlacel P135™ (Uniquema)
13 R908 Al/ZrTetrachlorohydrex glycine complex Reach 908™ - Reheis Inc
14 A418 Milled Macrospherical AACH A418™ - Summit
15 Z50 50% aqueous solution of Al/Zr pentachlorohydrate Zirconal 50™ - BK Giulini
16 R67* Water-modified AZAG Rezal 67™ modified in-house
22 36GP solid Al/Zr tetra-chlorhydrex glycine Rezal 36GP™ Reheis Inc
23 P5G Al/Zr pentachloro-hydrex glycine complex (RI 1.53 0) P5G™ (BK Giulini)
17 GOH Glycerin Glycerol - Aldrich
24 PG propane-1,2 -diol Fisher
25 DPG di(propane-1,2-diol) Fisher
26 TPnB tri(1,2-propanediol) n-butylether Dowanol TPnB™ - Dow Corning Inc
27 H3 0 silica H3 0™ - Wacker-Chemie GmbH
28 H3 0R X silica H3 0RX™ - Wacker-Chemie GmbH
29 H18 silica HI8™ - Wacker-Chemie GmbH
16 - R67* was made in house by freeze drying an AZAG solution (Rezal 67™) and sieving to obtain particulate solid free from hollow particles (-37% of particles particles of Example 1 - Structured Gels
In this Example, gels were made or attempted to be made in a number of representative organic solvents, using the structurants CDP1 to CDP13.
The gels were prepared in 30ml clear glass bottles. The solvent and gelling agent were weighed directly into the bottle to give a total mixture weight of lOg. A small Teflon™ stirrer bar was placed in the bottle and the mixture stirred and heated until the cyclo dipeptide had dissolved. The bottle was then removed from the heat and the solution allowed to cool and gel under quiescent conditions.
The ease of gel formation was assessed by determining for each of the cosmetic base formulations the temperature at which the CDP structurant dissolved in the chosen oil(s) and
if dissolution was observed, the temperature at which a gel formed on cooling the formulation. The results are summarised in Table 3.
These Examples and comparisons demonstrate the relative ease or difficulty of forming gelled cosmetic base formulations, depending on which oils are employed during the dissolution of the CDP structurant and the subsequent formation of a gel as the composition cools. The results are representative of corresponding formulations in which a cosmetic active is also introduced.
Examp1e/Comp 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Cl.l CI. 2 CI. 3 CI. 4
Ingredients % 3 3y weight
CDP1 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5
1-ISA 98.5 49.25 49.25 49.25 49.25
7-TN 49.25 98.5
8-245 49.25 98.5
9-364 49.25 98.5
10-704 49.25 91.1 98.5
Gel Formed? yes yes yes yes yes yes yes no yes yes no
Diss'n Temp °C 120 131 138 105 125 123 148 dnd 140 142 -150 dnd
Gelling Temp °C 35 65 65 43 41 46 75 - 79 126 -
Examp1e/Comp 1.8 1.9 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20
Ingredients % by weight
CDP2 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 3.75 4.0
1-ISA 98.5 49.25 49.25 49.25 24.62 49.25 12.02 26.88
3-BMA 7.4 12.02 9.60
7-TN 49.25 6.72
8-245 49.25 52.8
10-704 49.25 73.88 73.88 73.88 73.88 91.1 72.21
Gel Formed yes yes yes yes yes yes yes yes yes yes yes yes yes
Diss'n Temp °C 111 115 137 127 136 118 114 114 134 136 130 119 130
Gellng Temp °C 29 33 58 50 58 25 30 28 62 56 61 55 66
Examp1e/Comp 1.21 1.22 CI. 5 CI. 6 CI. 7 CI. 8 1.23 CI. 9 1.24 1.25 1.26 1.27
Ingredient % by weight
CDP2 15.0 3.0 1.5 1.5 1.5 3.75
CDP5 1.5 1.5
CDP6 1.5 1.5 1.5 1.5
1 - ISA 51.0 19.4 98.5 49.25 49.25
3 - BMA 34.0 9.7 24.62 14.77
8 - 245 98.5
7 - TN 98.5 49.25
9 - 364
10 - 704 67.9 98.5 98.5 73.88 98.5 49.25 83.73
Gel Formed? yes yes yes no yes yes yes no yes yes yes yes
Diss'n Temp °C 123 130 133 dnd 135 148 dnfd 134 dnd 140 145 130 140
Gelling Temp °C 69 70 84 98 -120 69 - 62 86 78 76
Example/Comp CI.10 CI.11 1.28 1.29 1.30 1.31 1.32 1.33 1. 34 1.35 CI. 12 1.36 1.37 CI. 13
Ingredient % by weight
CDP6 1.5 1.5
CDP7 1.5 1.5
CDP3 1.5 1.5
CDP10 1.5 1.5 1.5
CDP11 1.5 1.5 1.5
1 - ISA 98.5 24.62 98.5 98.5 49.25 98.5 98.5 24.62 98.5
3 - BMA 24.62
7 - TN 98.5 49.25
9 - 364
10 - 704 98.5 73.88 73.88 98.5 73.88 98.5
Gel Formed? yes yes yes yes yes yes yes yes yes yes yes yes yes yes
Diss'n Temp °C dnfd dnfd 113 134 107 138 150 130 111 139 dnfd 110 90 146
Gelling Temp °C 143 120 45 77 49 25 39 57 38 66 94 98 25 118
Composition (%) 1.38 CI. 14 1.39 1.40 CI. 15 1.41. CI. 16 1.42 CI. 17 1.43 CI. 18
CDP12 1.5 1.5
CDP13 1.5 1.5 1.5
CDP14 1.5 1.5
CDP15 0.5 0.5 1.5 1.5
1- ISA 98.5 24.62 99.5
3 - BMA 24.62 24.62 24.62
10 - 704 73.88 98.5 73.88 98.5 73.8 98.5 99.5 73.88 98.5
Gel Formed yes yes yes yes yes yes no yes no yes no
Dissolution Temperature (°C) 121 dnfd 85 95 102 148 DND 129 DND 128 DND 150
Gelling Temperature (°C) 58 128 25 25 79 95 42 75
In Table 3 above, dnd indicates that the structurant did not dissolve, and dnfd that it did not fully dissolve, in each case at 150°C unless otherwise indicated.
From Table 3, it can be seen that the employment of the specified monohydric alcohols, viz materials (1) to (6), enabled the resultant composition to gel at a lower temperature. Thus, for example, a comparison of Ex 1.2 with Cl.l shows that the CDP dissolved in the invention mixture at 131°C, but had not dissolved at 140°C in solely the volatile silicone. Similar improvements can be seen by comparing Ex 1.3 or 1.4 with CI.4 and CI.3 respectively. Of course, where the structurant had not dissolved, it could not subsequently form a distributed network through the carrier liquid and hence was not able to form a gel. Where it did dissolve, though at a higher temperature as in CI.3, the composition gelled at a much higher temperature of significantly over 100°C compared with the gelling temperature of the directly comparable invention composition, Ex 1.3. Ex 1.21 shows the formation of a concentrated solution/gel that can subsequently be diluted with other cosmetic oils during stick preparation.
Examples 2 to 5 - Cosmetic Stick Formulations
A number of cosmetic stick compositions were prepared, containing the ingredients specified in Tables 4 to 10 below. Their properties were measured by the methods described hereinafter and at the times indicated in the summaries.
Example 2 - Opaque Suspension Sticks
In Example 2, opaque sticks were made by dissolving the specified cyclo dipeptide structurant in isostearyl alcohol whilst with heated and stirring using an overhead paddle stirrer until complete dissolution had occurred. In formulations additionally containing GP1, the latter was dissolved into solution of the cyclo dipeptide structurant at a temperature of about 5 to 10°C lower. The remaining carrier oils were heated to approximately 50°C and stirred using a stirrer bar and the desired solid antiperspirant active was introduced slowly and with gentle stirring into them. When all the active had been added, the mixture was sheared using a Silverson mixer at 7000rpm for 5 minutes to ensure the active was fully dispersed. The active/oil mixture was then heated in an oven to 85°C and mixed into the structurant solution which had been allowed to cool to 90°C. The temperature of the stirred mixture was kept at 85CC until it was poured into conventional commercial 50g stick barrels and allowed to cool except for formulations containing GP1 which were poured at approximately 75°C.
The formulations and properties of the sticks are summarised in Table 4 below.
Example No 2.1 2.2 2.3 2.4 2.5
Ingredient % by weight
CDP2 2.5 2.5 1.5 1
LISA 35.75 35.75 30 28.2 30
7 TN 35.75 20.9
10.704 35.75 40 40
11.GP1 2.5 3 .0 2.5
13.R908 26.0 26.0 26.0 26.0 26.0
Hardness (mm) 16.5 15.2 13.8 18.6 14.3
pay.off (g)at t0 on WetorDry 0.35 0.25 0.31 0.27 0.3
whiteness t=24hr on WetorDry 13 16 14 27 20
pay.off (g)at t0 on wool 0.99 0.63 0.82 0.63 1.08
whiteness t=24hr on wool 17 17 16 15 20
From Table 4, it can be seen that sticks of acceptable firmness can be obtained using the invention structurants at comparatively low concentrations of the structurant and also in the presence of an additional structurant, also at a low concentration.
Example 3 - Transparent Suspension Sticks
The sticks in this Example were made using the process of Example 3 together with a preparatory step. In the preparatory step, the RI of the antiperspirant active was first measured using a standard procedure (Becke line test). The proportions of each of the carrier oils were then determined (through calculation and measurement) such that their weight averaged refractive index was closely matched to that of the active. In Example 3.8, the CDP structurant was fully dissolved in the mixture of monohydric alcohols before being mixed with the remainder of the carrier oils and subsequently with the antiperspirant active. The formulations are summarised in Table 5 below.
Example No 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9
Ingredient % by weight
CDP2 1.51 1.5 1.5 1.0 2.81
1-ISA 18.34 17.61 17.36 17.55 17.61 17.36 16.71 8.81
3-BMA 8.81 19.68
7-TN 12.21 22.83
10-704 55.03 52.89 52.14 52.7 52.89 52.14 54.29 42.36 29.47
11-GP1 3.0 4.0 4.05 3.5 4.0 3.0
14-A418 25.12 25.0 25.0 25.0 25.0 25.0 25.0 25.0
Hardness mm 23 14.7 13.1 16.1 14.8 n/d 16.2 14.0 20.1
Clarity %T 44 12.7 15.4 12.0 9.9 1.6% 0.7 23.0 6.1
Example No 3.10 3.11 3.12 3 .13 3.14 3.15 3 .16 3.17 3.18
Ingredient % by weight
CDP2 1.5 1.7 1.5 1.5 1.7 2.0
11 - GP1 2.0 4.0 2.0 2.0 4.0 4.0 4.0
18 - DBS 0.25 0.4
19 - 12-HSA 5.0
1 -ISA 17.8 18.46 15.51 15.735 16.14 17.98 15.848 15.916 15.32
10 - 704 53.45 52.48 52.99 53.765 55.16 51.1 54.152 54.384 53.30
3 - BMA 1.96 1.92 1.98
7 - TN
14 - A418 25.0 25.0 25.0 25.0 25.0 25.0 25.0
23 - P5G 25.0 25.0
Hardness mm 13.5 17.2 13.3 12.1 14.4 14.2 13.7 14.2 16.9
Clarity % T 19.4 15.3 12.2 2.2 13.2 26.6 27.5 15.0 8.7
Clarity -visualscore 2 3 0 -9 7 6 4 1 0
From Table 8, it can be seen that clear cosmetic sticks are obtainable using various combinations of oils as continuous carrier phase together with the CDP structurants, either alone or with a co-structurant.
Example 4 - Opaque Emulsion Sticks
In a first step in making opaque emulsion sticks according the present invention, a solution of the selected invention
structurant, and if present GP1, in ISA was made by the same method as in the process for making suspension sticks (Example 3). The remaining water immiscible carrier oils together with an emulsifier, Abil EM 90, were heated to 85°C in an oil bath whilst being shear mixed at 2500 rpm. The solution of antiperspirant active was heated to 80°C and introduced gradually into the oil/emulsifier mixture, and the resultant mixture was kept constant by heating at 85°C and sheared at 7500 rpm for 5 minutes. The emulsion was the mixed into the solution of the structurant solution which had been allowed to cool to ~ 90°C. The resultant mixture was stirred briefly to achieve complete mixing, poured into commercial 50g stick barrels at approximately 80°C and allowed to cool. The formulations and properties of the sticks are summarised in Table 9 below.
Example No 4.1 4.2
Ingredient % by weight
1-ISA 29.0 27.0
7-TN 29.0 27.0
12-EM90 0.5 0.5
15-Z50 40.0 40.0
Hardness (mm) 27.8 17.1
pay-off (g)at t0 on wool 0.66 0.80
whiteness t=24hr on wool 17 18
From Table 6, it can be seen that the use of the monohydric alcohol in conjunction with the other water-immiscible oils enables the emulsion formulations to be made quite easily.
Example 5 - Clear Emulsion Stick
In this Example, the general method of making emulsion sticks described in Example 5 was followed, preceded by a preparatory step for refractive index matching in order to obtain a translucent emulsion stick.
In the preparatory step, the refractive indices of the ingredients of the organic and aqueous phases in the emulsion were obtained or measured, and proportions of those ingredients estimated, based on calculation and measurement, such that the two phases had roughly matched refractive indices. The two phases containing the estimated proportions of ingredients were prepared, their refractive indices measured and the proportions of the carrier oils in the continuous (water-immiscible) phase were adjusted to the extent necessary to more closely match the RI of the disperse aqueous phase. In Example 5.2, the CDP structurant was fully dissolved in the mixture of monohydric alcohols before being mixed with the remainder of the carrier oils and subsequently with the antiperspirant active.
The Versamid polymer when employed was dissolved simultaneously with the cyclic dipeptide structurant. Any silica was incorporated in suspension in a fraction of the water-immiscible oil(s) and any antiperspirant active supplied as a solid was first dissolved in the specified weight of water.
The formulation and its properties are summarised in Table 7 below, in which nd indicates that a particular test was not carried out.
Example No 5.1 5.2 5.3 5.4 5.5
Ingredient % by weight
CDP2 1.5 2.0 2.0 1.5 2.0
1-ISA 21.14 12.84 18.51 20.92 43.45
7-TN 5.71 8.22 5.05 5.65
8-245 21.14 26.83 20.44 20.93 11.77
12-EM90 0.5 0.5 1.0 1.0 0.49
15-Z50 40.0 40.0 40.0 40.0
22 - 36GP 24.77
17- GOH 10.0 10.0 10.0 10.0
Hardness mm 18.6 16.1 13.4 11.9 17.2
Clarity % T 6.7 1.9 n/d n/d n/d
Clarity (visual score) 1 nd n/d n/d n/d
Example No 5.6 5.7 5.8 5.9 5.10
Ingredients % by weight
CDP2 2.0 2.0 2.0 1.5 1.5
1 - ISA 42.66 41.08 43.05 20.6 21.65
7 - TN 5.55 3.95
8 - 245 11.56 11.14 11.67 20.60 21.65
17 - GOH 10.0 10.0
15 - Z50 40.0 40.0
water 17.58 17.78 17.78
22 - 36GP 23.71 23.71
13 - R908 23.71
12 - EM90 0.49 0.49 0.49 0.75 0.75
20 - 930 1.0 2.0 1.0 1.0
27 -, H30 0.50
28 - H30RX 1.0 2.0
29 - H18 0.5
Hardness (mm) 14.4 19.9 17.2 14.8 14.7
Clarity (% T) 42.0 19.0 58.4 0.82 0.74
Clarity (visual score) 4 -1 7 n/d n/d
From Table 7 it can be seen not only that clear emulsion sticks can be made that include a faction of a water-miscible liquid, glycerol, but also that it can be made easily employing prior dissolution of the structurant in the monohydric alcohols.
i) Purity of CDP
The purity of CDP materials Al to A9 was measured by reverse
phase HPLC with ultraviolet (UV)detection.
A mobile phase was made comprising 300ml aliquot of
deionised water, to which was added a 700ml aliquot of HPLC
grade acetonitrile and 1.0ml of trifluoroacetic acid (Aldrich
spectrophotometric grade, TFA) and mixed thoroughly.
0.00lg of CDP sample was weighed into a 2 ml HPLC vial and
made up to volume with the mobile phase.
The sample was then analysed in a Hewlett Packard HPLC
analyser equipped with a Hypersil ODS 5mm C18, 250 x 4.6mm @
Room Temp column, a Hewlett-Packard 1050 Series Autosampler
and Hewlett-Packard 1050 UV Diode Array @ 210nm Detector.
The analysis was carried under the following conditions
Isocratic/gradient : Isocratic
Flow rate : 1.2ml/minute
Run time : 5 minutes
Temperature : Ambient
Injection volume : 20ml
ii) Dissolution Temperature
The dissolution temperature of the CDP was determined by forming a mixture of the particulate CDP and the selected carrier liquid at ambient temperature keeping the particulates in suspension with a mixer bar and raising the temperature of the mixture at a rate that was initially faster and later of approximately 2°C per minute as the dissolution temperature was approached more closely. The dissolution temperature was assessed as the temperature at which particulates were no longer visible.
iii) Gelling Temperature
The gelling temperature of a gelled oil phase was determined by first preparing a solution of the CDP in the selected oil(s) in glass tubes, having a diameter of 20mm and equipped with a glass thermometer resting on the bottom of the tube, in accordance with the description for Example 1 herein, and thereafter permitting the resultant solution in the tubes to cool naturally under quiescent conditions, ie without any cooling air being blown over the tubes and without the solution being stirred. External laboratory air temperature was about 23°C. Periodically, the thermometer was lifted by a few mm and if liquid had not flowed to fill the void under gravity, was carefully replaced on the tube bottom. The solution was considered to have formed a gel when it did not flow underneath the thermometer.
Stick Characterisation - Measurement of Properties iv) Stick hardness - Penetrometer
The hardness and rigidity of a composition which is a firm solid can be determined by penetrometry. If the composition is a softer solid, this will be observed as a substantial lack of any resistance to the penetrometer probe. A suitable procedure is to utilises a lab plant PNT penetrometer equipped with a Seta wax needle (weight 2.5 grams) which has a cone angle at the point of the needle
specified to be 9°10' ± 15'. A sample of the composition with a flat upper surface is used. The needle is lowered onto the surface of the composition and then a penetration hardness measurement is conducted by allowing the needle with its holder to drop under a total weight, (i.e. the combined weight of needle and holder) of 50 grams for a period of
five seconds after which the depth of penetration is noted. Desirably the test is carried out at a number of points on each sample and the results are averaged. Utilising a test of this nature, an appropriate hardness for use in an open-ended dispensing container is a penetration of less than 30 mm in this test, for example in a range from 2 to 3 0 mm. Preferably the penetration is in a range from 5mm to 20 mm.
In a specific protocol for this test measurements on a stick were performed in the stick barrel. The stick was wound up to project from the open end of the barrel, and then cut off to leave a flat, uniform surface. The needle was carefully lowered to the stick surface, and then a penetration hardness measurement was conducted. This process was carried out at six different points on the stick surface. The hardness reading quoted is the average value of the 6 measurements.
v) Deposition by firm sticks (pay-off)
Another property of a composition is the amount of it which is delivered onto a surface when the composition is drawn across that surface (representing the application of a stick product to human skin), sometimes called the pay-off. To carry out this test of deposition when the composition is a firm stick, able to sustain its own shape, a sample of the composition with standardised shape and size is fitted to apparatus which draws the sample across a test surface under standardised conditions. The amount, transferred to the surface is determined as an increase in the weight of the substrate to which it is applied. If desired the colour, opacity or clarity of the deposit may subsequently be
determined. A specific procedure for such tests of deposition and whiteness applicable to a firm solid stick used apparatus to apply a deposit from a stick onto a substrate under standardised conditions and then measures the mean level of white deposits using image analysis.
The substrates used were:
a: 12 x 28cm strip of grey abrasive paper (3M™ P800
WetorDry™ Carborundum paper)
b: 12 x 28cm strip of black Worsted wool fabric. The substrates were weighed before use. The sticks were previously unused and with domed top surface unaltered.
The apparatus comprised a flat base to which a flat substrate was attached by a clip at each end. A pillar having a mounting to receive a standard size stick barrel was mounted on an arm that was moveable horizontally across the substrate by means of a pneumatic piston.
Each stick was kept at ambient laboratory temperature overnight before the measurement was made. The stick was advanced to project a measured amount from the barrel. The barrel was then placed in the apparatus and a spring was positioned to biassed the stick against the substrate with a standardised force. The apparatus was operated to pass the stick laterally across the substrate eight times. The substrate was carefully removed from the rig and reweighed. The whiteness of the deposit could subsequently be measured as described at (v) below.
vi) Whiteness of Deposit
The deposits from the at test (ii) above, were assessed for
their whiteness shortly after application (ie within 30
minutes) or after an interval of 24 hours approximately.
This was done using a Sony XC77 monochrome video camera with a Cosmicar 16mm focal length lens positioned vertically above a black table illuminated from a high angle using fluorescent tubes to remove shadowing. The apparatus was initially calibrated using a reference white card, after the fluorescent tubes had been turned on for long enough to give a steady light output. A cloth or Carborundum paper with a deposit thereon from the previous test was placed on the table and the camera was used to capture an image. An area of the image of the deposit was selected and analysed using a Kontron IBAS™ image analyser. This notionally divided the image into a large array of pixels and measured the grey level of each pixel on a scale of 0 (black) to 255 (white). The average of the grey intensity was calculated. This was a measure of the whiteness of the deposit, with higher numbers indicating a whiter deposit. It was assumed that low numbers show a clear deposit allowing the substrate colour to be seen.
vii) Clarity of formulation - Light transmission
The translucency of a composition may be measured by placing a sample of standardised thickness in the light path of a spectrophotometer and measuring transmittance, as a percentage of light transmitted in the absence of the gel.
This test was carried out using a dual-beam Perkin Elmer Lambda 40 spectrophotometer. The sample of composition was poured hot into a 4.5 ml cuvette made of polymethylmethacrylate) (PMMA) and allowed to cool to an ambient temperature of 20-25°C. Such a cuvette gives a 1 cm thickness of composition. Measurement was carried out at 580 nm, with an identical but empty cuvette in the reference beam of the spectrophotometer, after the sample in the cuvette had been held for 24 hours. A transmittance measured at any temperature in the range from 20-25°C is usually adequately accurate, but measurement is made at 22°C if more precision is required.
viii) Clarity of Formulation - Visual assessment score
A gel contained within a 1cm thick cuvette was placed directly on to a sheet of white paper on which 21 sets of figures where printed in black. The size and thickness of the figures varied systematically and were numbered from -12 (the largest, thickest set) through 0 to 8 (the smallest thinnest set) The score given to each gel was the highest numbered set which could be read clearly through the gel, the higher the number, the higher the clarity.
1. A cosmetic composition comprising:-
(i) a cosmetic active material
(ii) a continuous phase which comprises a monohydric alcohol having a melting point of below 3 0°C and a boiling point of greater than 100°C and optionally at least one water-
immiscible liquid carrier oil
a structurant for the continuous phase which comprises a cyclodipeptide having the general formula 1
in which at least one of Ri and R2 which may be the same or different represents an aliphatic group that is optionally substituted by an aromatic or cycloaliphatic group and the other may alternatively represent hydrogen.
2. A composition according to claim 1 in which the
monohydric alcohol has a melting point of below 20°C and a boiling point of greater than 120°C.
3. A composition according to claim 2 in which the
monohydric alcohol is selected from linear or branched
aliphatic alcohols or benzyl alcohol that satisfy such melting and boiling point criteria.
4. A composition according to claim 3 in which the monohydric alcohol is iso-stearyl alcohol and/or benzyl alcohol.
5. A composition according to any preceding claim in which the continuous phase comprises at least 5% by weight monohydric alcohol.
6. A composition according to claim 5 in which the continuous phase comprises from 2 0 to 80% monohydric alcohol.
7. A composition according to any preceding claim in which one of Ri and R2 represents an aliphatic ester group of formula - (CH2)n-C02-R3 in which n is an integer of at least 1 and R3 represents an alkyl, cycloalkyl or aryl group.
8. A composition according to any preceding claim in which one of Ri and R2 represents a phenyl polymethylene group.
9. A composition according to claim 8 in which Ri represents -CH2-Ph.
10. A composition according to claim 8 or 9 in which R2 represents an aliphatic ester of formula -CH2-C02-R3 in R3 represents a carbocyclic or heterocyclic group.
11. A composition according to claim 10 in which R3 represents a single ring, optionally bridged.
12. A composition according to claim 10 or 11 in which R3 comprises a carbocylic or heterocyclic group that is substituted by at least one alkyl substituent.
13. A composition according to claim 12 in which the alkyl substituent is methyl or isopropy1.
14. A composition according to claim 11 in which the ring in R3 is a cyclohexane or benzene ring substituted by a methyl and an isopropyl group that are para to each other.
15. A composition according to claim 10 in which R3 is derivable from thymol, isopinocamphenol or a 3,5-dialkyl cyclohexanol.
16. A composition according to claim 15 in which R3 is derivable from thymol.
17. A composition according to claim 10 in which the 3,5-dialkyl cyclohexanol is 3,5-dimethyl cyclohexanol.
18. A composition according to any preceding claim in which the cyclodipeptide is present at a concentration of from 0.1 to 15% by weight of the composition.
19. A composition according to claim 18 in which the cyclodipeptide is present at a concentration of from 0.3
to 10% by weight of the composition.
20. A composition according to claim 19 in which the cyclodipeptide is present at a concentration of from 0.5 to 5% by weight of the composition.
21. A composition according to claim 18 in which the cyclodipeptide is present at a concentration of from 0.4 to 8% by weight of the continuous phase.
22. A composition according to any one of the preceding claims characterised in that the water-immiscible oil comprises a silicone oil and/or a non-silicone hydrophobic organic liquid selected from hydrocarbons, hydrophobic aliphatic esters, aromatic esters and hydrophobic ethers.
23. A composition according to any one of the preceding claims wherein the water-immiscible carrier liquid contains silicone oil in an amount which is at least 10% by weight of the composition.
24. A composition according to any one of the preceding claims which contains not more than 3% by weight of any fatty alcohol which is solid at 2 0°C.
25. A composition according to any preceding claim in which the cyclo dipeptide is employed in conjunction with a further structurant comprising an N-acyl amino acid derivative.
26. A composition according to claim 25 in which the further structurant is N-lauroyl glutamic acid dibutylamide.
27. A composition according to any one of claims 1 to 24 in which 12-hydroxystearic acid is employed as a further structurant.
28. A composition according to any one of claims 1 to 24 in which a polyamide is employed as a further structurant.
29. A composition according to any one of claim 25, 26, 27 or 28 in which the further structurant is employed in a weight ratio to the cyclo dipeptide of from 1:10 to 10:1.
30. A composition according to any one of claims 1 to 24 in which a further structurant comprising a dibenzylidene alditol is employed.
31. A composition according to claim 30 in which dibenzylidene sorbitol is employed at a weight ratio to the cyclodipeptide structurant of from 1:3 to 1:10.
32. A composition according to any preceding claim in which the composition comprises a suspension of the cosmetic active in the structured hydrophylic carrier liquid.
33. A composition according to claim 32 in which the carrier liquid and the suspended cosmetic active have matched refractive indices and has a light transmission of at least 1%.
34. A composition according to any one of claims 1 to 31 wherein the composition is an emulsion with the cosmetic active in solution in a hydrophilic, preferably water-miscible, disperse phase.
35. A composition according to claim 34 wherein the disperse phase contains a diol or polyol.
36. A composition according to claim 35 wherein the disperse phase contains glycerol or 1,2-propane diol.
37. A composition according to any of claims 34 to 36 in which the composition contains from 0.1% to 10% by weight of a nonionic emulsifier.
38. A composition according to claim 37 in which the emulsifier is an alkyl dimethicone copolyol.
39. A composition according to any of claims 34 to 38 in which the refractive indices of the disperse and continuous phases of the emulsion are matched.
40. A cosmetic composition according to any preceding in which the cosmetic active is an antiperspirant deodorant active.
41. A composition according to claim 40 in which the antiperspirant active comprises an aluminium and/or zirconium halohydrate, an activated aluminium and/or zirconium halohydrate, or an aluminium and/or zirconium complex or an activated aluminium and/or zirconium
42. A composition according to claim 40 in which the complex contains both aluminium and zirconium.
43. A composition according to any one of the preceding claims which contains from 5 to 4 0% by weight of the antiperspirant active.
44. An cosmetic product comprising a dispensing container having an aperture for delivery of a stick, means for urging the contents of the container to the said aperture or apertures, and a composition according to any one of the preceding claims accommodated within the container.
45. A product according to claim 44 wherein the composition is a firm gel such that a penetrometer needle with a cone angle of 9 degrees 10 minutes, drops into the gel for no more than 30mm when allowed to drop under a total weight of 50 grams for 5 seconds.
46. A process for the production of a composition according to any one of claims 1 to 45 comprising the steps of:-
a) forming a mixture containing a liquid carrier, a structurant dissolved therein, and a solid or a disperse liquid phase comprising cosmetic active in particulate or dissolved form at a temperature of at least 40°C and is above the setting temperature of the mixture;
b) introducing the mixture into a mould which preferably is a dispensing container, and
c) cooling or permitting the mixture to cool to ambient temperature, characterised in that
the structurant is a cyclo dipeptide that satisfies the general formula 1:-
in which at least one of R1 and R2 which may be the same or different represents an aliphatic group that is optionally substituted by an aromatic or cycloaliphatic group and the other may alternatively represent hydrogen,
and the carrier comprises a monohydric alcohol having a melting point of below 3 0°C and a boiling point of greater than 100°C, and optionally at least one water-immiscible liquid carrier oil.
47. A process according to claim 46 in which the carrier comprises at least one water-immiscible liquid carrier oil and at least 5% monohydric alcohol.
48. A process according to claim 47 in which the carrier comprises from 20 to 80% by weight monohydric alcohol.
49. A process according to any of claims 46 to 48 in which the water-immiscible liquid carrier comprises a silicone
oil and/or an aromatic ester.
50. A process according to claim 46 in which the cyclo dipeptide structurant is dissolved in the monohydric alcohol and up to half of the water-immiscible oil prior to being mixed with the water-immiscible oil or a residual fraction thereof.
51. A process according to any of claims 46 to 50 which includes a step of pouring the mixture at elevated temperature into a dispensing container and allowing it to cool therein so as to produce a product according to claim 40 or 41.
52. A cosmetic method for preventing or reducing perspiration on human skin comprising topically applying to the skin a composition according to any one of claims 1 to 44.
Dated this 31st day of July 2007
COSMETIC COMPOSITIONS COMPRISING A CYCLODIPEPTIDE COMPOUND
An improved process for the preparation of cosmetic formulations containing a cosmetic active and a continuous phase comprising a water-immiscible liquid carrier, that are structured by a cyclo dipeptide (CDP) having the general formula in which R1 and/or R2, which may be the same or preferably different, each represents a hydrocarbon or alkylene ester group and the other may alternatively represent hydrogen,which employs a monohydric alcohol having a melting point of below 30oC and a boiling point of greater than 100oC and a cosmetic active material optionally together with at least one water-immiscible liquid carrier oil to assist in the dissolution of the structurant and modify the gelling temperature of the resultant mixture. Preferably, the CDP is dissolved in the monohydric alcohol and optionally up to half the water-immiscible oil prior to being mixed with the remaining ingredients of the composition.
|Indian Patent Application Number
|PG Journal Number
|Date of Filing
|Name of Patentee
|HINDUSTAN UNILEVER LIMITED
|HINDUSTAN LEVER HOUSE, 165/166 BACKBAY RECLAMATION, MUMBAI.
|PCT International Classification Number
|PCT International Application Number
|PCT International Filing date