Surfactant-free oil-in-water type emulsion, process for preparation thereof and its uses

Abstract

There is described an oil-in-water emulsion free of surfactant agents comprising: A) At least a cross-polymer acrylate/alkyl-acrylate or derivatives thereof, or mixtures thereof in the aqueous phase of the emulsion; b) At least a polyacrylate or derivatives thereof, or mixtures thereof in the oily phase of the emulsion, and c) At least a neutralizing agent. Further, the present invention refers to a process of obtaining a surfactant-free emulsion and its use in cosmetics and pharmaceuticals compositions. The emulsion in question can be applied to all kinds of skin, being also indicated for people with sensitive skin.

Claims

1. Oil-in-water emulsion characterized by comprising: i) at least an acrylate/alkyl-acrylate cross-polymer, or mixtures thereof in the aqueous phase of the emulsion; and ii) at least a polyacrylate, or mixtures thereof in the oily phase of the emulsion, iii) at least a neutralizing agent, said emulsion being free of surfactants and preservatives.

2. Emulsion according to claim 1, wherein the cross-polymer acrylate/alkyl acrylate cross-polymer can be selected from the group that comprises: acrylate/C10-30 alkyl-acrylate cross-polymer, poly C10-30 alkyl-acrylate, Potassium Acrylates/C10-30 Alkyl Acrylate cross-polymer, Sodium Acrylates/C10-30 Alkyl Acrylate cross-polymer, or derivatives thereof, and mixtures thereof.

3. Emulsion according to claim 2, wherein the acrylate/alkyl acrylate cross-polymer is the acrylate/C10-30 alkyl-acrylate cross-polymer.

4. Emulsion according to claim 1, wherein the polyacrylate is selected from the group that comprises: Potassium Aluminum polyacrylate, Potassium polyacrylate, Sodium polyacrylate, Sodium polyacrylate Starch, Ammonium polyacrylate and Glyceryl polyacrylate, or derivatives thereof, and mixtures thereof.

5. Emulsion according to claim 4, wherein the polyacrylate is sodium polyacrylate.

6. Emulsion according to claim 1, comprising a) of about 0.05 to about 5.00% in mass of the acrylate/alkyl-acrylate cross-polymer or derivatives thereof in the aqueous phase of the emulsion; and b) of about 0.1 to about 10.0% in mass of the polyacrylate and/or derivatives thereof in the oily phase of the emulsion; being all percentages based on the total mass of the composition.

7. Emulsion according to claim 6, comprising: a) of about 0.15 to about 0.25% in mass of the acrylate/alkyl-acrylate cross-polymer and/or derivatives thereof and b) of about 1 to about 2% in mass of the polyacrylate and/or derivatives thereof, being all the percentages calculated based on the total mass of the formulation.

8. Emulsion according to claim 1, wherein the neutralizing agent is selected from the group comprising triethanolamine, sodium hydroxide, potassium hydroxide and aminomethylpropanol and derivatives, and mixtures thereof.

9. Emulsion according to claim 1, wherein the neutralizing agent is present in a sufficient quantity to result in a pH about 6.

10. Emulsion according to claim 1, further comprising a hydrophilic polysaccharide selected from the group that comprises: gellan gum, xanthan gum, modified xanthan gums and derivatives of modified amides.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) The invention refers to an oil-in-water (O/W) type emulsion comprising:

(2) a) At least a acrylate/alkyl-acrylate cross-polymer or derivatives thereof, or mixtures thereof in the aqueous phase of the emulsion; and

(3) b) At least a polyacrylate or derivatives thereof, or mixtures thereof in the oily phase of the emulsion,

(4) c) At least a neutralizing agent,

(5) being free of surfactants.

(6) According to a preferred embodiment, the present invention refers to an oil-in-water emulsion comprising:

(7) a) of about 0.05 to about 5.00% of at least a acrylate/alkyl-acrylate cross-polymer or derivatives thereof, or mixtures thereof in the aqueous phase of the emulsion; and

(8) b) of about 0.1 to about 10.0% of a polyacrylate or derivatives thereof, or mixtures thereof in the oily phase of the emulsion; and all the percentages are based on the total mass of the composition.

(9) c) at least a neutralizing agent in a sufficient quantity that results in a pH value of about 6;

(10) being free of surfactants.

(11) In an even more preferred embodiment of the present invention, the surfactant-free oil-in-water emulsion comprises of about 0.15 to about 0.25% in mass of at least a acrylate/alkyl-acrylate cross-polymer or derivatives thereof, or mixtures thereof and of about 1 to about 2% in mass of a polyacrylate or derivatives thereof, or mixtures thereof and these percentages are calculated based on the total mass of the formulation.

(12) a) Acrylate/Alkyl-Acrylate Cross-Polymer

(13) Among the options of acrylate/alkyl-acrylate cross-polymers that can be added to the emulsion object of this invention are: acrylate/C10-30 alkyl-acrylate cross-polymer, poly C10-30 alkyl-acrylate, Potassium acrylate/C10-30 alkyl-acrylate cross-polymer, Sodium acrylate/C10-30 alkyl acrylate cross-polymer.

(14) Preferably, the acrylate/alkyl-acrylate cross-polymer to be added to the emulsion in question is the acrylate/C10-30 alkyl-acrylate cross-polymer.

(15) The acrylate/alkyl-acrylate cross-polymer to be added to the emulsion should basically be a hydrosoluble polymer, which may also present high dispersibility in the oily phase of the emulsion.

(16) Essentially, the acrylate/C10-30 alkyl-acrylate cross-polymer acts like an emulsifying polymer of the formulation and is a component that is compatible with most of the cosmetic adjuvants usually employed in emulsion, such as oils and emollient esters and co-solvents, film-forming and wetting agents, preservatives, chelating agents and antioxidants, fragrances, colorings and even low HLB value surfactants.

(17) The acrylate/alkyl-acrylate cross-polymer should be present in the aqueous phase of the oil-in-water emulsion free of emulsifying agents.

(18) Commercially, the acrylate/C10-30 alkyl-acrylate cross-polymer can be found under the name “Permulen® TR1 or TR2” manufactured by the company Noveon—The Specialty Chemical Innovator. The difference between Permulen TR1 and Permulen TR2 consists of the degree of viscosity provided to the final emulsion. Permulen TR1 drift in a more viscous emulsion, having a jellified appearance and Permulen TR2 drift in a more fluid emulsion, less consistent in appearance.

(19) More preferably, the acrylate/alkyl-acrylate cross-polymer to be added to the emulsion in question is Pemulen TR2.

(20) The cross-polymer acrylate/alkyl-acrylate is present in the emulsion presented herein in a quantity that varies between 0.05 to 5% in mass, preferably from 0.15 to 0.25% in mass, based on the total mass of the composition.

(21) b) Polyacrylate

(22) Among the options of polyacrylates that can be added to the emulsion that is the object of this invention are: Potassium Aluminum Polyacrylate, Potassium Polyacrylate, Sodium Polyacrylate, Sodium Polyacrylate Starch, Ammonium Polyacrylate and Glyceryl Polyacrylate.

(23) Preferably, the polyacrylate to be added to the emulsion object of the present invention is sodium polyacrylate. Commercially, said sodium polyacrylate can be found under the name “Cosmedia® SP” manufactured by the company Cognis-carechemicals.

(24) The polyacrylate belongs to the group of polymers and has a broad variety of applications in industry, including use as sequestering agent, consistency agent, and absorption agent in disposable diapers, among others.

(25) The polyacrylate should be present in the oily phase of the oil-in-water emulsion free of emulsifying agents.

(26) The polyacrylate is present in the emulsion presented herein in a quantity that varies between 0.1 to 10% in mass, preferably from 1 to 2% in mass, based on the total mass of the composition.

(27) b) Neutralizing Agent

(28) The neutralizing agent of the present invention can be chosen from the group that comprising triethanolamine, sodium hydroxide, potassium hydroxide and aminomethylpropanol or any other neutralizing agent known on the market that acts in the same way as those already mentioned, as well as mixtures thereof.

(29) The neutralizing agent is present in the emulsion presented herein in a sufficient quantity to adjust the pH value to about 6.

(30) c) Optional Components

(31) The emulsion according to this invention may optionally comprise components usually used in cosmetic or pharmaceutical products according to the application sought for the composition to be prepared. The optional components include: antioxidant agents, preservatives, film formers, microcrystalline web support formers, co-solvent polymeric agents and/or copolymeric agents, denaturants, consistency agents, emollients, wetting and/or moisturizing agents and conditioners, but is not limited to these alone.

(32) In a preferred embodiment of the present invention, the surfactant-free oil-in-water emulsion comprises as optional component, of about 0.05 to about 4% in mass, preferably of about 0.1% to about 0.3% in mass of a hydrophilic polysaccharide, being this percentage calculated based on the total mass of the formulation.

(33) Among the options of hydrophilic polysaccharides that can be present in the emulsion that is the object of the present invention are: gellan gum, xanthan gum, modified xanthan gums and derivatives of modified amides.

(34) Preferably, the hydrosoluble polysaccharide to be added to the emulsion that is the object of this invention is selected from among the group of gums. More specifically, the polysaccharide preferably used in this emulsion is a xanthan gum.

(35) In a preferred embodiment of the present invention, the oil-in-water emulsion free of emulsifying agents comprises, in a physiologically acceptable vehicle, of about 0.05 to about 4.00% in mass, preferably of about 0.1 to about 0.3% in mass of xanthan gum, and this percentage is calculated based on the total mass of the formulation.

(36) Optionally, the present invention further comprises an active ingredient that can be selected, for example, from among the group: sun screens (UV), anti-inflammatory agents, tranquilizers, moisturizers, collagen and elastine synthesis stimulators, anti-microbians, cell renewal agents, among others.

(37) Further, in a preferred embodiment of the present invention, the emulsion is free of preservatives, which renders the irritability potential even lower, being particularly indicated for sensitive skin for this reason also.

(38) By means of the combination between the acrylate/alkyl-acrylate cross-polymer, polyacrylate and, optionally, xanthan gum, we have developed an emulsion without the need to use surfactants. Consequently, the absence of surfactants means the emulsion is less allergenic and less irritating to the skin, which makes it particularly indicated for individuals with sensitive skin.

(39) Further, the optional absence of preservatives of the present invention results in an emulsion with an even lower allergenic and irritating potential, being particularly beneficial for individuals with sensitive skin.

(40) Additionally, the combination between the polymers referred to above provides the emulsion chemical and chemical-physical stability, that is, there is no separation between the phases of the emulsion at rest, nor is there the loss of functionality of the active ingredients eventually added. The use of the polymers separately results in an unstable formulation or with an unsuitable sensation for cosmetic use.

(41) The emulsion according to the present invention presents viscosity and sensation suitable for cosmetic and pharmaceutical use.

(42) Examples of galenic forms for the use of surfactant-free emulsions are: Fluid or semi-solid emulsion, for example: Body moisturizing milk; Moisturizing milk for the face; Body moisturizing lotion; Moisturizing lotion for the face; Emulsions for sensitive skin. Sun screens or blocks for adults or children, whether or not designed for simultaneous use while playing sports; Body or facial moisturizers; Anti-signs products for body and face; Firming products for body and face; Self-tanning products; Insect repellant products; Body or facial skin-lightening moisturizers; Anti-cellulite products;

(43) A surfactant-free oil-in-water emulsion object of the present invention presents other physical and chemical characteristics that are suitable and safe for the user of this product, such as: Appropriate texture during application, non-sticky and non-oily; Good spreadability and glide during application; Low quantity of oily residue on skin after application; Low comedogenicity; Improved skin hydration as it does not remove the skin's hydrolipidic layer; Better skin compatibility.

(44) Process of Preparing of the Emulsion Object of the Present Invention

(45) To obtain the results of the present invention, it is strictly necessary to following the phases in which the compulsory components should be present in the preparation process, namely: the acrylate/alkyl-acrylate cross-polymer should be added in the aqueous phase of the emulsion and the sodium polyacrylate should be added in the oily phase of the emulsion.

(46) Preferentially, the emulsion production process described here comprises the following steps:

(47) a) Add in a first recipient the acrylate/alkyl-acrylate cross-polymer and, optionally, a xanthan gum in the aqueous phase of the emulsion and stir with rotation at about 2500 rpm, while heating, until the temperature reaches 75° C. to 85° C. (about 10 min.);

(48) b) Separately, in a second recipient, stir with maximum rotation of 2500 rpm the oily phase of the emulsion, including the polyacrylate, while heating until the temperature reaches 75° C. to 85° C. (about 10 min.);

(49) c) When both phases are at a temperature of 75° C. to 85° C., pour the contents of the second recipient (the oily phase) into the first recipient (the aqueous phase) and stir with rotation at about 2500 rpm for about 10 minutes, keeping the temperature between 75° C. and 85° C.;

(50) d) After concluding step c), begin cooling, keeping the system under stirring at about 2500 rpm;

(51) d′) Optionally, add adjuvants when the system reaches a temperature between 50° and 55° C. under stirring at about 3000 rpm;

(52) e) Add neutralizing agents when the temperature of the cooled system obtained in d) reaches 40° to 45° C. under stirring at about 3000 rpm;

(53) f) Cool the system to about 35° C. under stirring at about 3000 rpm.

(54) Said stirring is preferably obtained by means of a reactor which may be one commonly used in the industry, preferably a turbine reactor, more preferably the reactor used is a Koruma™ reactor.

(55) It is important to underline that the combination between acrylate/alkyl-acrylate cross-polymer and sodium polyacrylate is absolutely necessary to obtain the results presented herein.

(56) The results achieved in the present invention are not achieved by using singly polymers. The use of polyacrylate alone, for example, results in an unstable formulation, whereas the use of acrylate/alkyl-acrylate cross-polymer alone gives the formulation a gelatinous consistency or extremely fluid, depending on the concentration in which the polymer is used. Accordingly, the use of singly polymers results in an unsuitable formulation for cosmetic products due to their instability and unattractive consistency.

(57) It must also be highlighted that it is fundamental that the polymers be added in the specific phases described in the present invention, that is to say, the acrylate/alkyl-acrylate cross-polymer should be added in the aqueous phase and the polyacrylate should be added in the oily phase of the emulsion. Reversing the phases or adding the polymers together in the same phase results in an unstable emulsion.

EXAMPLES

(58) Table 1 shows an example of the sunscreen emulsion O/W type free of surfactants prepared according to the present invention:

(59) TABLE-US-00001 TABLE 1 Example of cosmetic composition Concentration INCI name Function (% in mass) WATER QSP Qsp ACRYLATES/C10-30 ALKYL Consistency 0.10 ACRYLATE CROSSPOLYMER Agent CYCLOPENTASILOXANE Emollient 10.00 CYCLOPENTASILOXANE/ Emollient 5.00 DIMETHICONE CROSSPOLYMER DICAPRYLYL CARBONATE Emollient 5.00 DISODIUM EDTA Chelating Agent 0.05 GLICERET-26 Wetting Agent 6.00 SODIUM HIDROXIDE Neutralizing 0.01 Agent ISONONYL ISONONANOATE Emollient 4.00 ASTROCARYUM MURUMURU Emollient 0.50 BUTTER C12-C15 ALKYL BENZOATE Emollient 3.00 XANTHAN GUM Consistency 0.10 Agent THEOBROMA GRANDIFLORUM Emollient 0.50 SEED BUTTER GLICERIN Wetting Agent 5.00 PENTYLENE GLYCOL Wetting Agent 5.00 ETHYLHEXYLGLYCERIN Emollient 5.00 SODIUM POLYACRYLATE Consistency 1.00 Agent

Example 2

(60) Clinical Evaluation of Cutaneous Tolerance to Cosmetic Compositions Containing the Emulsion of the Present Invention after Repeated Applications

(61) The aim of this evaluation was to verify the cutaneous compatibility and the absence of sensations of discomfort after 5 consecutive applications under controlled conditions of a product having the following composition:

(62) Selected volunteers were evaluated by a dermatologist to check their skin conditions to take part in this study. Subsequently, on 12 (twelve) volunteers considered apt to participate in the test, a skin area of 40 cm.sup.2 was sectioned in indelible ink on the right forearm of each volunteer taking part in the study.

(63) The product was applied in a uniform manner on said sectioned area twice per day for four days running: the first application of the day was performed at a clinic and the second at the home of each volunteer. On the fifth day after the start of the test, a single application was made. The applications made at the clinic had the following procedure: the product was applied to the marked region and the arm remained flexed for 15 minutes and extended for 30 consecutive minutes. In the home application, the volunteers were advised to apply the product and keep their arm in a normal position for 60 minutes and note down any sensation of discomfort.

(64) After 24, 48, 72 and 96 hours from the start of the study, the volunteers returned to the clinic for a reading of the region, a new application and a new reading. On the fifth day (120 hours after the start of the study) the volunteers returned to the clinic for the last application of the product and final evaluation.

(65) Before taking the readings, the volunteers were advised to remove the product with plenty of water. The readings were carried out and noted down, and the data collected was tabulated as shown below. Additionally, after the final stage of the schedule of applications of the product the volunteers underwent a further dermatological evaluation which compared the volunteers' initial skin conditions before taking part in the study with the conditions presented at the end of the test.

(66) Results:

(67) Interpreting the results was based on the cutaneous evaluation and the recording of the sensations of discomfort during the application of the product. The results were tabulated and determined based on the calculation of the ratio of reactive volunteers with the total number of volunteers who concluded the study. The cutaneous compatibility of the product was considered very good, good, moderate or bad, according to the following scale:

(68) TABLE-US-00002 TABLE 2 Cutaneous Compatibility Classification Percentage of volunteers Percentage of volunteers displaying clinical feeling sensations of Cutaneous signs attributed to discomfort attributed to Compatibility the test product the test product Very good 0 0 Good 0 <30 Moderate <20 +/− 0 30 to 50 Bad ≧20 Presence or absence 0 50 Very good: absence of clinical signs or sensations of discomfort; Good: absence of local clinical signs but with some sensation of discomfort in less than 30% of the volunteers; Moderate: presence of clinical signs in at least 20% of the volunteers, with or without sensation or discomfort or sensation of discomfort felt by 30-50% of the volunteers; Bad: presence of clinical signs on 20% of the volunteers, with or without sensation of discomfort or sensation of discomfort felt by 30-50% of the volunteers.

(69) Results:

(70) TABLE-US-00003 TABLE 3 Data from the evaluation of the clinical signs Days of Study Vol 1 2 3 4 5 1 − − − − − 2 − − − − − 3 − − − − − 4 − − − − − 5 − − − − − 6 − − − − − 7 − − − − − 8 − − − − − 9 − − − − − 10 − − − − − 11 − − − − − 12 − − − − − Total frequency of appearances (sum) per day Total 0 0 0 0 0 Positive (+) 0 0 0 0 0 Positive (++) 0 0 0 0 0 Positive (+++) 0 0 0 0 0 Negative (−) = Injury absent Positive (+) = Light erythema (hardly perceptible, with undefined edges and without edema) Positive (++) = Clear erythema (definable with clear edges, delimited and associated to edema) Positive (+++) = Erythema + edema + papules/vesicles

(71) TABLE-US-00004 TABLE 4 Descriptions of discomfort detected at Clinic Days of Use Vol 1 2 3 4 1 0 0 0 0 2 0 0 0 0 3 0 0 0 0 4 0 0 0 0 5 0 0 0 0 6 0 0 0 0 7 0 0 0 0 8 0 0 0 0 9 0 0 0 0 10 0 0 0 0 11 0 0 0 0 12 0 0 0 0

(72) TABLE-US-00005 TABLE 5 Descriptions of discomfort detected at home Days of Use Vol 1 2 3 4 1 0 0 0 0 2 0 0 0 0 3 0 0 0 0 4 0 0 0 0 5 0 0 0 0 6 0 0 0 0 7 0 0 0 0 8 0 0 0 0 9 0 0 0 0 10 0 0 0 0 11 0 0 0 0 12 0 0 0 0

(73) The following concepts were taken into account upon filling out the tables:

(74) TABLE-US-00006 Group Compatible descriptions — None 1 Burning sensation; local heat 2 Itching; irritation 3 Pins and needles; tingling 4 Burning accompanied by itching 5 Burning accompanied by tingling 6 Itching accompanied by tingling 7 Burning with itching and tingling 8 Other - Subgroup A The sensation is transient, lasts some minutes, but then goes away (only mark subgroup when there is discomfort). Subgroup B The sensation lasts for over 15 minutes. Subgroup X The intensity of the sensation is light. Subgroup Y The intensity of the sensation is moderate or intense.

(75) The above results can be summarized as follows:

(76) TABLE-US-00007 Percentage of Percentage of Clinical volunteers displaying Sensations of volunteers feeling Signs clinical signs discomfort sensations of discomfort 0 0% 0 0%

(77) Under the conditions in which the product described was evaluated and in the sample of volunteers studied, the data allow the conclusion that the cutaneous compatibility of the product is considered very good.

BIBLIOGRAPHIC REFERENCES

(78) IDSON, Bernard. Effects of Emulsifiers on Skin. Cosmetics & Toiletries, v. 106, p. 43-51, May 1991 RIEGER, Martin M.; RHEIN, Linda D. Surfactants in cosmetics. 2. ed. New York: Marcel Dekker, Inc. 1997 IARC, Re-evaluation of Some Organic Chemicals, Hydrazine and Hydrogene Peroxide, v. 71, p. 43, 1999