CLIAMS:1. An oil-in-water nanoemulsion comprising
a) water in an amount ranging from 20 to 65% wt.;
b) oil in an amount ranging from 5 to 15% wt.; and
c) non-ionic surfactant in an amount ranging from 25 to 68% wt;

wherein particle size of the nanoemulsion ranges from 20 and 200 nanometers; and wherein the nanoemulsion is formed spontaneously.

2. The oil-in-water nanoemulsion as claimed in claim 1, wherein said oil is selected from a group comprising medium chain mono, di and triglycerides such as Capric/caprylic triglycerides; natural oils and mixtures thereof.

3. The oil-in-water nanoemulsion as claimed in claim 2, wherein said natural oils are selected form a group comprising olive oil, almond oil, avacado oil, jojoba oil, argan oil, wheat-germ oil, tea tree oil.

4. The oil-in-water nanoemulsion as claimed in claim 1 wherein said non ionic surfactants are selected from a group consisting of polyethylene glycol derivative of natural oils especially polyethylene glycol derivative of Ricinus communis (Castor) Oil, polyoxyethylene fatty acid ester of sorbitan especially polyoxyethylene sorbitan monolaurate, 2-Octyl 1 dodecan 1 ol, Polyoxyethylene glycol (40) Hydrogenated Castor Oil, Polyoxyethylene glycol (40) Sorbitan Perisostearate, Polyoxyethylene glycol (40) Stearate , Polyoxyethylene glycol (80) Glyceryl Cocoate, Polyoxyethylene glycol (120) Methyl Glucose Dioleate, Polyoxyethylene glycol (150) Distearate, Polyoxyethylene glycol (200) Hydrogenated Glyceryl Palmate, Polyglyceryl-3 Caprate, Polyglyceryl-3 Caprylate, Polyglyceryl-3 Methylglucose Distearate, Polyglyceryl-3 Diisotearate, Polyglyceryl-3 Oleate, Polyglyceryl-4 Caprate, Polyglyceryl-4 Laurate, Polyglyceryl-4 Isostearate, Polyglyceryl-6 Isostearate, Polyglyceryl-6 Dioleate, Polyoxyethylene glycol (20) Sorbitan monolaurate, Polyoxyethylene glycol (20) Sorbitan monostearate, Polyoxyethylene glycol (20) Sorbitan monooleate, Polyoxyethylene glycol (8) Caprylic/Capric Glycerides and combinations thereof.

5. A process for the preparation of oil-in-water nanoemulsion comprising steps of

a) weighing required amount of oil(s) and surfactant(s) in a container and stir mix well to form a mixture; and
b) adding water to the mixture of step 1 while stirring to obtain transparent/translucent nanoemulsion system of the present invention.

wherein the process is carried out at an ambient temperature of 20-400C.

6. A process for the preparation of oil-in-water nanoemulsion comprising steps of

a) weighing required amount of oil(s) and surfactant(s) in a container and stir mix well to form a mixture;
b) adding water to the mixture of step 1 while stirring to obtain thick transparent/translucent system;
c) optionally adding oil soluble actives / solution of water soluble actives to system of step 2 to obtain transparent/translucent system containing actives;
d) diluting system of step 2 or 3 suitably to obtain nanoemulsion

wherein the process is carried out at an ambient temperature of 20-400C

7. A process for the preparation of oil-in-water nanoemulsion comprising steps of

a) weighing required amount of oil(s) and surfactant(s) in a container and stir mix well to form a mixture;
b) optionally adding oil soluble actives / solution of water soluble actives to system of step 1 to obtain transparent/translucent system containing actives;
c) adding water to the mixture of step 2 while stirring to obtain transparent/translucent nanoemulsion system of the present invention

wherein the process is carried out at an ambient temperature of 20-400C

8. The process as claimed in claim 6 and 7, wherein amount of said water soluble actives ranges from 0.1 to 10 wt%.

9. The process as claimed in claim 6 and 7, wherein amount of said oil soluble actives ranges from 0.1 to 10 wt%. ,TagSPECI:Field of the invention

The present invention relates to nanoemulsion. More particularly the present invention relates to oil-in-water nanoemulsion, a process for its preparation and its uses in cosmetics and dermatological applications/products.

Background of the invention

Nanoemulsions are visibly transparent or translucent colloidal systems, falling in the size regime of 20-500 nm, which can be of oil-in-water (O/W) or water-in-oil (W/O) type. These typical non-equilibrated colloidal systems have multifarious composition and preparative route dependent properties. Nanoemulsions have been known since the last 20 years, mainly for nanoparticle preparation. Very recently, however, direct applications of nanoemulsions have been made in fields of consumer products such as in pharmaceuticals and cosmetics. This is because of an increased understanding of their efficacious applications as delivery systems. As compared to conventional emulsion systems, nanoemulsions provide improved bioavailability and bioefficacy of lipophilic bioactives in their delivery. Notably, nanoemulsions also have stunning transporting ability and controlled release, which is highly desirable, in the realm of pharmaceuticals, cosmetic and personal care. Nanoemulsions also allow composition making by use of low levels of surfactants and oils and high levels of water thus providing efficient hydration / moisturization systems. Additionally, nanoemulsions render possible different visual aspects; richness and skin feel in a great variety of products such as lotions, transparent milks and crystal-clear gels, with different rheological behavior, properties thus providing biophysical and sensorial benefits highly valued by consumers.

Generally in the conventional method of preparation of nanoemulsions involvement of significant amount of energy (high pressure homogenizers, heating/cooling steps) and/or the use of ethoxylated emulsifiers are quite common. Thus conventionally nanoemulsions are formed by an application of external shear force to rupture larger droplets into smaller ones, which is achieved by using sophisticated devices such as high-pressure microfluidic devices (for rupturing droplets in concentrated emulsions to smaller one), high pressure homogenization, sonication, high pressure membrane filtration and the like.

One of the well-known approaches for processing nanoemulsions is by phase inversion temperature (PIT) method which makes use of the temperature-dependent phase behavior of ethoxylated emulsifiers. Upon cooling of a water/oil emulsion, phase inversion to an oil/water nanoemulsion occurs. The ultra-low interfacial tension between water and oil phase, at this inversion region, allows the formation of very fine oil/water emulsion droplets. Another favoured approach for formulation of nanoemulsion is high pressure homogenization, whereby cosmetic matrix is produced by reduction in size of emulsion.

US 2004/0151746 relates to a process of preparation of nanoemulsion composition for cosmetic use, where in the preferable amounts of fatty compounds , non ionic surfactants and water used are in the ranges of 4-12% by weight, 8-20% by weight and 65-90% by weight respectively. The process involves the steps of mixing and agitation of fatty phase and nonionic surfactants at a temperature above their melting points, under normal atmospheric pressure, followed by addition of water and at least one cationic surfactant to form cationic nanoemulsion composition of oil-in –water type with an average particle size of 100nm.

US6375960 relates to a transparent and stable nanoemulsion, that includes an oily phase dispersed in an aqueous phase; and at least one surfactant that is solid at a temperature of less than or equal to 45° C, selected from ethoxylated fatty ethers and ethoxylated fatty esters, and mixtures thereof; wherein the oily phase includes oil globules having a number-average size of less than 100 nm and the oily phase includes at least one oil having a molecular weight of greater than 400; and wherein a weight ratio of the oily phase to the surfactant ranges from 2 to 10. The oily phase of the composition more preferably ranges from 5 to 30% by weight with respect to the total weight of the nanoemulsion, while the proportion of surfactant ranges from 1 to 8% by weight with respect to the total weight of the nanoemulsion. The invention also discloses a process for making the nanoemulsion, and methods for its use. The nanoemulsions according to this invention preferably have a transparent to bluish appearance with a transmittance coefficient at 600 nm more preferably ranging from 20 to 85%.

US 2013/0011454 relates to oil-in-water type (O/W) type nanoemulsion composition comprising an oil component containing oil and a polyethylene glycol ester-based emulsifier; and a water component containing a polyol or a polyol derivative. The polyethylene glycol ester-based emulsifier is present in an amount of 0.1-10 wt % based on the total weight of the composition while the oil is present in an amount of 1-20 wt % based on the total weight of the composition. The invention also relates to a cosmetic composition comprising the oil-in-water type nanoemulsion composition, and to a method for preparing the oil-in-water type nanoemulsion composition.

Further US ‘454 discloses a nano-sized low-viscosity emulsion having a high inner phase can be obtained through the method that is different from the conventional methods of phase inversion temperature emulsification or high pressure emulsification, thereby significantly improving the stability of the emulsion. Further the nanoemulsion composition of US ‘454 can be added to a variety of cosmetic compositions having a variety of methods of use and can thus deliver active ingredients to the skin effectively since it has small-sized particles.

EP0728460 discloses an oil-in-water nanoemulsion whose oil globules have a lower average size than 100 nm and comprising an amphiphilic lipid phase containing non-ionic amphiphilic lipids are liquid at ambient temperature below 45 °C and their use as a topical application in cosmetics and in particular dermopharmacy. Further EP ‘460 also discloses that the nanoemulsion comprises of oil, lipids and surfactant.

US6461625 relates to a nanoemulsion based on a surfactant chosen from alkoxylated alkenyl succinates, alkoxylated alkenyl succinates of glucose and alkoxylated alkenyl succinates of methylglucose and at least one oil having a molecular weight greater than 400, where the ratio by weight of the amount of oily phase to the amount of surfactant from 2 to 10. According to ‘625, the emulsion comprises additives for improving the transparency of the formulation. These additives are preferably chosen from the group formed by: lower alcohols comprising from 1 to 8 carbon atoms and more particularly from 2 to 6 carbon atoms, such as ethanol; glycols such as glycerol, propylene glycol, 1,3-butylene glycol, dipropylene glycol, pentylene glycol, isoprene glycol and polyethylene glycols comprising from 4 to 16 and preferably 8 to 12 ethylene oxide units; sugars such as glucose, fructose, maltose, lactose and sucrose.

Although the prior arts discussed above and many other patent applications including US20120251596, EP615741, EP406162, EP1010416, EP1430867, US4533254, EP1353629 and US8357639 disclosed the preparation processes for Nanoemulsions, a need still remains in the art for the spontaneous preparation of nanoemulsion compositions at ambient temperature and /or pressure conditions without the requirement of addition of specific ingredients / agents.

Nanoemulsion compositions can be prepared using energy intensive approaches as evident from the above cited prior arts. Hence there is a long felt need for nanoemulsion compositions and preparation methods by which nanoemulsions can be prepared spontaneously, essentially without requirement of energy intensive techniques and or addition of specific ingredients.
The formulation of nanoemulsion based cosmetics involves breaking micron sized emulsion to nanozised smaller particles. Conventional methods for breaking the larger particles to smaller particles involve uses of high pressure homogenization, ultra sonication, phase inversion temperature etc. Therefore the conventional production of nanoemulsion requires either significant amount energy (high pressure homogenization, ultra sonication, heating/cooling steps) and/or the use of ethoxylated emulsifiers. The production of naoemulsion according to the phase inversion temperature (PIT) method requires use of the temperature-dependent phase behavior of ethoxylated emulsifiers. The use of ethoxylated emulsifiers and the large energy consumption that is required for the heating/cooling steps is crucial when using the standard PIT method for the production of nanoemulsions.

The major disadvantages of using conventional procedures are
· Consumption of high energy that impart cost to the production process
· Use of specialized instruments (High pressure homogenizer, ultra sonication etc) that impart cost to the production process

High temperature leads to limitation in incorporating temperature sensitive active ingredients in nanoemulsion.

The present invention does not require the addition of specific ingredients such as lower alcohols comprising from 1 to 8 carbon atoms and more particularly from 2 to 6 carbon atoms, such as ethanol; glycols such as glycerol, propylene glycol, 1, 3-butylene glycol, dipropylene glycol, pentylene glycol, isoprene glycol and polyethylene glycols, which are otherwise required to maintain the transparency in nanoemulsions as stated in US ‘625.

The present invention provides a process for the preparation of nanoemulsion without using energy intensive techniques and or addition of specific ingredients. Addition of specific ingredients leads to overload of non-essential ingredients in the formulation. Amongst other things, this adds to cost of the final formulation. Hence there is a long felt need for method of nanoemulsion preparation using minimum ingredients.

Object of the present invention

An object of the present invention is to overcome the drawbacks of the prior art.

Another object of the present invention is to provide an Oil-in-Water (O/W) nanoemulsion with a particle size that ranges from 20 to 250 nm and comprising water, oil and surfactants.

Yet another object of the present invention is to spontaneously prepare nanoemulsions at ambient temperature, without using high pressure homogenization or high phase inversion temperatures in the process.

Yet another object of the present invention is to prepare nanoemulsion without using energy intensive techniques and or addition of specific ingredients.

Summary of the present invention

An aspect of the present invention is to provide an oil-in-water nanoemulsion comprising
a. water in an amount ranging from 20 to 65% wt.;
b. oil in an amount ranging from 5 to 15% wt.; and
c. non-ionic surfactant in an amount ranging from 25 to 68% wt;

wherein particle size of the nanoemulsion ranges from 20 and 200 nanometers; and wherein the nanoemulsion is formed spontaneously.

Another aspect of the present invention is to provide a process for the preparation of oil-in-water nanoemulsion comprising steps of
a. weighing required amount of oil(s) and surfactant(s) in a container and stir mix well to form a mixture; and
b. adding water to the mixture of step 1 while stirring to obtain transparent/translucent nanoemulsion system of the present invention.

wherein the process is carried out at an ambient temperature of 20-400C.

Yet another aspect of the present invention is to provide a process for the preparation of oil-in-water nanoemulsion comprising steps of

a. weighing required amount of oil(s) and surfactant(s) in a container and stir mix well to form a mixture;
b. adding water to the mixture of step 1 while stirring to obtain thick transparent/translucent system;
c. optionally adding oil soluble actives / solution of water soluble actives to system of step 2 to obtain transparent/translucent system containing actives;
d. diluting system of step 2 or 3 suitably to obtain nanoemulsion

wherein the process is carried out at an ambient temperature of 20-400C

Yet another aspect of the present invention is to provide a process for the preparation of oil-in-water nanoemulsion comprising steps of
a. weighing required amount of oil(s) and surfactant(s) in a container and stir mix well to form a mixture;
b. optionally adding oil soluble actives / solution of water soluble actives to system of step 1 to obtain transparent/translucent system containing actives;
c. adding water to the mixture of step 2 while stirring to obtain transparent/translucent nanoemulsion system of the present invention

wherein the process is carried out at an ambient temperature of 20-400C

Description of the invention

The present invention provides nanoemulsion compositions that are spontaneously prepared by mixing water, oil and surfactants at specific amounts at ambient temperature of 20-400C but without using high pressure homogenization or high phase inversion temperatures or ultrasonic rupturing of the composition. The nanoemulsion composition of the present invention can be used for cosmetic or dermatological applications.

The nanoemulsions comprise of oily particles dispersed in an aqueous phase, wherein the particle size of said particles is preferably between 20 and 200 nanometers. Nanoemulsions according to the present invention comprise 20 to 65% of water, 5 to 15% Oil and 25 to 68% of surfactants. It is observed that when the composition of the nanoemulsion essentially falls within the ranges stated, the nanoemulsion is formed spontaneously. When any of the three components are added at a wt/wt % range outside the above specified range may lead to formation of cloudy or phase separated systems with higher particle size (µm) or polydisperse system. Further, these nanoemulsions having oil drops with small grain size are physically stable for longer periods under storage and dilution conditions.

Specifically the invention discloses oil-in-water nanoemulsion comprising:
a. water in an amount ranging from 20 to 65% wt.;
b. oil in an amount ranging from 5 to 15% wt.; and
c. non-ionic surfactant in an amount ranging from 25 to 68% wt;

wherein particle size of the nanoemulsion ranges from 20 and 200 nanometers; and wherein the nanoemulsion is formed spontaneously.

The oils used in the preparation of nanoemulsions according to the present invention may be selected from a group comprising: medium chain di and triglycerides such as caprylic/capric triglycerides; natural oils; and mixtures thereof. The natural oils used in this case may be selected from the a group comprising of olive oil, almond oil, avacado oil, Jojoba oil, argan oil, wheat-germ oil, tea tree oil.

The surfactant(s) used in the preparation of nanoemulsions according to the present invention are non-ionic surfactants and may be selected form a group comprising: polyethylene glycol derivative of natural oils especially polyethylene glycol derivative of Ricinus communis (Castor) Oil, polyoxyethylene fatty acid ester of sorbitan especially polyoxyethylene sorbitan monolaurate, 2-Octyl 1 dodecan 1 ol, Polyoxyethylene glycol (40) Hydrogenated Castor Oil, Polyoxyethylene glycol (40) Sorbitan Perisostearate, Polyoxyethylene glycol (40) Stearate , Polyoxyethylene glycol (80) Glyceryl Cocoate, Polyoxyethylene glycol (120) Methyl Glucose Dioleate, Polyoxyethylene glycol (150) Distearate, Polyoxyethylene glycol (200) Hydrogenated Glyceryl Palmate, Polyglyceryl-3 Caprate, Polyglyceryl-3 Caprylate, Polyglyceryl-3 Methylglucose Distearate, Polyglyceryl-3 Diisotearate, Polyglyceryl-3 Oleate, Polyglyceryl-4 Caprate, Polyglyceryl-4 Laurate, Polyglyceryl-4 Isostearate, Polyglyceryl-6 Isostearate, Polyglyceryl-6 Dioleate, Polyoxyethylene glycol (20) Sorbitan monolaurate, Polyoxyethylene glycol (20) Sorbitan monostearate, Polyoxyethylene glycol (20) Sorbitan monooleate, Polyoxyethylene glycol (8) Caprylic/Capric Glycerides and combinations thereof.

The composition comprises essentially of non-ionic surfactants. Other surfactants are optional and may be added if the specific formulation so requires. As an example if the final product required is a cleansing nanoemulsion then apart from the non-ionic surfactant, anionic surfactant may also be added. Thus the nanoemulsion of the present invention allows addition of other surfactants but these are not essential / critical to the formation of the nanoemulsion of the present invention.

An embodiment of the present invention provides a method for preparing the said nanoemulsions comprising the following process steps:

Process 1:

Step 1: Weigh required amount of oil(s) and surfactant(s) in a container and stir mix well to form a mixture.
Step 2: Add water to the mixture of step 1 while stirring to obtain transparent/translucent nanoemulsion system of the present invention.

Process 2:

Step 1: Weigh required amount of oil(s) and surfactant(s) in a container and stir mix well to form a mixture.
Step 2: Add water to the mixture of step 1 while stirring to obtain thick transparent/translucent system.
Step 3: Optionally add oil soluble actives / solution of water soluble actives to system of step 2 to obtain transparent/translucent system containing actives.
Step 4: Dilute system of step 2 or 3 suitably to obtain nanoemulsion of current invention.
Observation: A thick transparent/translucent gel was formed that upon dilution converted to a nanaoemulsion having particle size ranging from 15 - 150 nm. Transmittance of the system was 75%.

Process 3:

Step 1: Weigh required amount of oil(s) and surfactant(s) in a container and stir mix well to form a mixture.
Step 2: Optionally add oil soluble actives / solution of water soluble actives to system of step 1 to obtain transparent/translucent system containing actives.
Step 3: Add water to the mixture of step 2 while stirring to obtain transparent/translucent nanoemulsion system of the present invention.

The term “water soluble active” is defined as and includes those cosmetically suitable additives as are hydrophilic and/or soluble in water.

The term “oil soluble active” is defined as and includes those cosmetically suitable additives as are soluble in oil.

The oil soluble active and water soluble active as may be added to the nanoemulsion composition of the present invention may be selected from surface-active substances (surfactants, emulsifiers), other oil components, consistency factors, thickeners, superfatting agents, stabilizers, polymers, silicone compounds, lecithins, phospholipids, biogenic agents, UV protection factors, antioxidants, deodorants, antiperspirants, antidandruff agents, film formers, swelling agents, insect repellents, self-tanning agents, tyrosinase inhibitors (depigmenting agents), hydrotropes, solubilizers, preservatives, perfume oils, dyes, etc.

The amount of water soluble actives ranges from 0.1 to 10 wt%.

The amount of oil soluble actives ranges from 0.1 to 10 wt%.

The quantities of the particular additives are governed by the particular application envisaged.

The present invention may further comprise one or more of the listed conventional ingredients. However these all are optional ingredients. These are not critical to the working of the present invention. Optional ingredients are added to make specific final products as per the present invention. the optional ingredients are not essential to the preparation of nanoemulaion by simple stirring process. It may be noted that when non-ionic surfactants, oil and water are added at stated wt/wt% the nanoemulsion is formed by simple mixing process. The optional ingredients are active ingredients as are added to provide the final formulation. Such as antiageing ingredient may be added to the nanoemulsion of the present invention to provide an antiageing nanoemulsion product; thickener may be added to provide the suitable consistency to the product; and UV protectant / antioxidant may be provided for protection against UV / free radicals.

Surface-Active Substances

The surface-active substances present may be anionic, nonionic, cationic and/or amphoteric or zwitterionic surfactants or emulsifiers or a mixture thereof. In surfactant-containing cosmetic preparations such as, for example, shower gels, foam baths, shampoos, etc., at least one anionic surfactant is preferably present. Creams and lotions preferably contain nonionic surfactants/emulsifiers.

Typical examples of anionic surfactants are soaps, alkyl benzene-sulfonates, alkanesulfonates, olefin sulfonates, alkylether sulfonates, glycerol ether sulfates, a-methyl ester sulfonates, sulfofatty acids, alkyl sulfates, fatty alcohol ether sulfates, glycerol ether sulfates, fatty acid ether sulfates, hydroxy mixed ether sulfates, monoglyceride (ether) sulfates, fatty acid amide (ether) sulfates, mono- and dialkyl sulfosuccinates, mono- and dialkyl sulfosuccinamates, sulfotriglycerides, amide soaps, ether carboxylic acids and salts thereof, fatty acid isethionates, fatty acid sarcosinates, fatty acid taurides, N-acylamino acids such as, for example, acyl lactylates, acyl tartrates, acyl glutamates and acyl aspartates, alkyl oligoglucoside sulfates, protein fatty acid condensates (particularly wheat-based vegetable products) and alkyl (ether) phosphates. If the anionic surfactants contain polyglycol ether chains, they may have a conventional homolog distribution although they preferably have a narrow-range homolog distribution.

Typical examples of nonionic surfactants are polyethylene glycol derivative of natural oils especially polyethylene glycol derivative of Ricinus communis (Castor) Oil, polyoxyethylene fatty acid ester of sorbitan especially polyoxyethylene sorbitan monolaurate, 2-Octyl 1 dodecan 1 ol, Polyoxyethylene glycol (40) Hydrogenated Castor Oil, Polyoxyethylene glycol (40) Sorbitan Perisostearate, Polyoxyethylene glycol (40) Stearate , Polyoxyethylene glycol (80) Glyceryl Cocoate, Polyoxyethylene glycol (120) Methyl Glucose Dioleate, Polyoxyethylene glycol (150) Distearate, Polyoxyethylene glycol (200) Hydrogenated Glyceryl Palmate, Polyglyceryl-3 Caprate, Polyglyceryl-3 Caprylate, Polyglyceryl-3 Methylglucose Distearate, Polyglyceryl-3 Diisotearate, Polyglyceryl-3 Oleate, Polyglyceryl-4 Caprate, Polyglyceryl-4 Laurate, Polyglyceryl-4 Isostearate, Polyglyceryl-6 Isostearate, Polyglyceryl-6 Dioleate, Polyoxyethylene glycol (20) Sorbitan monolaurate, Polyoxyethylene glycol (20) Sorbitan monostearate, Polyoxyethylene glycol (20) Sorbitan monooleate, Polyoxyethylene glycol (8) Caprylic/Capric Glycerides and combinations thereof.

Typical examples of cationic surfactants are quaternary ammonium compounds, for example dimethyl distearyl ammonium chloride, and esterquats, more particularly quaternized fatty acid trialkanolamine ester salts.

Typical examples of amphoteric or zwitterionic surfactants are alkylbetaines, alkylamidobetaines, amino-propionates, aminoglycinates, imidazolinium betaines and sulfobetaines. The surfactants mentioned are all known compounds.

Typical examples of particularly suitable mild, i.e. particularly dermatologically compatible, surfactants are fatty alcohol polyglycol ether sulfates, monoglyceride sulfates, mono- and/or dialkyl sulfosuccinates, fatty acid isethionates, fatty acid sarcosinates, fatty acid taurides, fatty acid glutamates, a-olefin sulfonates, ether carboxylic acids, alkyl oligo-glucosides, fatty acid glucamides, alkylamidobetaines, amphoacetals and/or protein fatty acid condensates, preferably based on wheat proteins.

Oil Components

Oil components and emollients contribute towards further optimizing sensory properties of cosmetic formulations. Suitable oil components are, for example, Guerbet alcohols based on fatty alcohols containing 6 to 18 and preferably 8 to 10 carbon atoms, esters of linear C6-22 fatty acids with linear or branched C6-22 fatty alcohols or esters of branched C6-13 carboxylic acids with linear or branched C6-22 fatty alcohols such as, for example, myristyl myristate, myristyl palmitate, myristyl stearate, myristyl isostearate, myristyl oleate, myristyl behenate, myristyl erucate, cetyl myristate, cetyl palmitate, cetyl stearate, cetyl isostearate, cetyl oleate, cetyl behenate, cetyl erucate, stearyl myristate, stearyl palmitate, stearyl stearate, stearyl isostearate, stearyl oleate, stearyl behenate, stearyl erucate, isostearyl myristate, isostearyl palmitate, isostearyl stearate, isostearyl isostearate, isostearyl oleate, isostearyl behenate, isostearyl oleate, oleyl myristate, oleyl palmitate, oleyl stearate, oleyl isostearate, oleyl oleate, oleyl behenate, oleyl erucate, behenyl myristate, behenyl palmitate, behenyl stearate, behenyl isostearate, behenyl oleate, behenyl behenate, behenyl erucate, erucyl myristate, erucyl palmitate, erucyl stearate, erucyl isostearate, erucyl oleate, erucyl behenate and erucyl erucate. Also suitable are esters of linear C6-22 fatty acids with branched alcohols, more particularly 2-ethyl hexanol and isopropanol, esters of C18-38 alkylhydroxycarboxylic acids with linear or branched C6-22 fatty alcohols, more especially Dioctyl Malate, esters of linear and/or branched fatty acids with polyhydric alcohols (for example propylene glycol, dimer diol or trimer triol) and/or Guerbet alcohols, triglycerides based on C6-10 fatty acids, liquid mono-, di- and triglyceride mixtures based on C6-18 fatty acids, esters of C6-22 fatty alcohols and/or Guerbet alcohols with aromatic carboxylic acids, more particularly benzoic acid, esters of C2-12 dicarboxylic acids with linear or branched alcohols containing 1 to 22 carbon atoms or polyols containing 2 to 10 carbon atoms and 2 to 6 hydroxyl groups, vegetable oils, branched primary alcohols, substituted cyclohexanes, linear and branched C6-22 fatty alcohol carbonates, such as Dicaprylyl Carbonate (Cetiol® CC) for example, Guer-bet carbonates based on C6-18 and preferably C8-10 fatty alcohols, esters of benzoic acid with linear and/or branched C6-22 alcohols (for example Finsolv® TN), linear or branched, symmetrical or nonsymmetrical dialkyl ethers containing 6 to 22 carbon atoms per alkyl group, such as Dicaprylyl Ether (Cetiol® OE) for example, ring opening products of epoxidized fatty acid esters with polyols, silicone oils (cyclomethicone, silicon methicone types, etc.) and/or aliphatic or naphthenic hydrocarbons such as, for example, mineral oil, Vaseline, petrolatum, isohexadecanes, squalane, squalene or dialkyl cyclohexanes.

Thickeners

Suitable thickeners are, for example, Aerosil® types (hydrophilic silicas), polysaccharides, more especially xanthan gum, guar-guar, agar-agar, alginates and tyloses, carboxymethyl cellulose and hydroxyethyl and hydroxypropyl cellulose, polyacrylates (for example Carbopols® and Pemulen types [Goodrich]; Synthalens® [Sigma]; Keltrol types [Kelco]; Sepigel types [Seppic]; Salcare types [Allied Colloids]), polyacrylamides, polymers, polyvinyl alcohol and polyvinyl pyrrolidone. Other consistency factors which have proved to be particularly effective are bentonites, for example Bentone® Gel VS-5PC (Rheox) which is a mixture of cyclopentasiloxane, Disteardimonium Hectorite and propylene carbonate, and a sodium polyacrylate known as Cosmedia® SP. Other suitable consistency factors are electrolytes, such as sodium chloride and ammonium chloride.

Stabilizers

Metal salts of fatty acids such as, for example, magnesium, aluminium and/or zinc stearate or ricinoleate may be used as stabilizers.

UV Protection Factors and Antioxidants

UV protection factors in the context of the invention are, for example, organic substances (light filters) which are liquid or crystalline at room temperature and which are capable of absorbing ultraviolet radiation and of releasing the energy absorbed in the form of longer-wave radiation, for example heat. UV-B filters can be oil-soluble or water-soluble. The following are examples of oil-soluble substances:

3-benzylidene camphor or 3-benzylidene norcamphor and derivatives thereof, for example 3-(4-methylbenzylidene)-camphor; 4-aminobenzoic acid derivatives, preferably 4-(dimethylamino)-benzoic acid-2-ethylhexyl ester, 4-(dimethylamino)-benzoic acid-2-octyl ester and 4-(dimethylamino)-benzoic acid amyl ester; esters of cinnamic acid, preferably 4-methoxycinnamic acid-2-ethylhexyl ester, 4-methoxycinnamic acid propyl ester, 4-methoxycinnamic acid isoamyl ester, 2-cyano-3,3-phenylcinnamic acid-2-ethylhexyl ester (Octocrylene); esters of salicylic acid, preferably salicylic acid-2-ethylhexyl ester, salicylic acid-4-isopropylbenzyl ester, salicylic acid homomethyl ester; derivatives of benzophenone, preferably 2-hydroxy-4-methoxybenzo-phenone, 2-hydroxy-4-methoxy-4'-methylbenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone; esters of benzalmalonic acid, preferably 4-methoxybenzalmalonic acid di-2-ethylhexyl ester; triazine derivatives such as, for example, 2,4,6-trianilino-(p-carbo-2'-ethyl-1'-hexyloxy)-1,3,5-triazine and Octyl Triazone or Dioctyl Butamido Triazone (Uvasorb® HEB); propane-1,3-diones such as, for example, 1-(4-tert.butylphenyl)-3-(4'-methoxyphenyl)-propane-1,3-dione; ketotricyclo(5.2.1.0) decane derivatives.

Suitable water-soluble substances are 2-phenylbenzimidazole-5-sulfonic acid and alkali metal, alkaline earth metal, ammonium, alkylammonium, alkanolammonium and glucammonium salts thereof and 2,2-(1,4-phenylene)-bis-1H-benzimidazole-4,6-disulfonic acid and salts thereof, more particularly the sodium salt; sulfonic acid derivatives of benzophenones, preferably 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid and salts thereof; sulfonic acid derivatives of 3-benzylidene camphor such as, for example, 4-(2-oxo-3-bornylidenemethyl)-benzene sulfonic acid and 2-methyl-5-(2-oxo-3-bornylidene)-sulfonic acid and salts thereof.

Typical UV-A filters are, in particular, derivatives of benzoyl methane such as, for example, 1-(4'-tert.butylphenyl)-3-(4'-methoxyphenyl)-propane-1,3-dione, 4-tert.butyl-4'-methoxy-dibenzoyl methane (Parsol® 1789) or 1-phenyl-3-(4'-isopropylphenyl)-propane-1,3-dione and enamine compounds. The UV-A and UV-B filters may of course also be used in the form of mixtures. Particularly favorable combinations consist of the derivatives of benzoyl methane, for example 4-tert.butyl-4'-methoxydibenzoylmethane (Parsol® 1789) and 2-cyano-3,3-phenylcinnamic acid-2-ethyl hexyl ester (Octocrylene) in combination with esters of cinnamic acid, preferably 4-methoxycinnamic acid-2-ethyl hexyl ester and/or 4-methoxycinnamic acid propyl ester and/or 4-methoxycinnamic acid isoamyl ester.

Combinations such as these are advantageously combined with water-soluble filters such as, for example, 2-phenylbenzimidazole-5-sulfonic acid and alkali metal, alkaline earth metal, ammonium, alkylammonium, alkanolammonium and glucammonium salts thereof.
Besides the soluble substances mentioned insoluble light-blocking pigments, i.e. finely dispersed metal oxides or salts may also be used for this purpose. Examples of suitable metal oxides are, in particular, zinc oxide and titanium dioxide. Silicates (talcum), barium sulfate and zinc stearate may be used as salts. The oxides and salts are used in the form of the pigments for skin-care and skin-protecting emulsions.

Besides the two groups of primary sun protection factors mentioned above, secondary sun protection factors of the antioxidant type may also be used. Secondary sun protection factors of the antioxidant type interrupt the photochemical reaction chain which is initiated when UV rays penetrate into the skin.

Biogenic Agents

In the context of the invention, biogenic agents are, for example, tocopherol, tocopherol acetate, tocopherol palmitate, ascorbic acid, (deoxy) ribonucleic acid and fragmentation products thereof, f3-glucans, retinol, bisabolol, allantoin, phytantriol, panthenol, AHA acids, amino acids, ceramides, pseudoceramides, essential oils, plant extracts, for example prunus extract, bambara nut extract, and vitamin complexes.

Deodorants

Deodorants counteract, mask or eliminate body odors. Body odors are formed through the action of skin bacteria on apocrine perspiration which results in the formation of unpleasant-smelling degradation products. Accordingly, deodorants contain active principles which act as germ inhibitors, enzyme inhibitors, odor absorbers or odor maskers.
Germ Inhibitors

Basically, suitable germ inhibitors are any substances which act against gram-positive bacteria such as, for example, 4-hydroxybenzoic acid and salts and esters thereof, N-(4-chloro-phenyl)-N'-(3,4-dichlorophenyl)-urea, 2,4,4'-trichloro-2'-hydroxy-diphenylether (triclosan), 4-chloro-3,5-dimethylphenol, 2,2'-methylene-bis-(6-bromo-4-chlorophenol), 3-methyl-4-(1-methyl-ethyl)-phenol, 2-benzyl-4-chlorophenol, 3-(4-chlorophenoxy)-propane-1,2-diol, 3-iodo-2-propinyl butyl carbamate, chlorhexidine, 3,4,4'-trichlorocarbanilide (TTC), antibacterial perfumes, thymol, thyme oil, eugenol, clove oil, menthol, mint oil, farnesol, phenoxyethanol, glycerol monocaprate, glycerol monocaprylate, glycerol monolaurate (GML), diglycerol monocaprate (DMC), salicylic acid-N-alkylamides such as, for example, salicylic acid-n-octyl amide or salicylic acid-n-decyl amide.

Enzyme Inhibitors

Suitable enzyme inhibitors are, for example, esterase inhibitors. Esterase inhibitors are preferably trialkyl citrates, such as trimethyl citrate, tripropyl citrate, triisopropyl citrate, tributyl citrate and, in particular, triethyl citrate (Hydagen® CAT). Esterase inhibitors inhibit enzyme activity and thus reduce odor formation. Other esterase inhibitors are sterol sulfates or phosphates such as, for example, lanosterol, cholesterol, campesterol, stigmasterol and sitosterol sulfate or phosphate, dicarboxylic acids and esters thereof, for example glutaric acid, glutaric acid monoethyl ester, glutaric acid diethyl ester, adipic acid, adipic acid monoethyl ester, adipic acid diethyl ester, malonic acid and malonic acid diethyl ester, hydroxycarboxylic acids and esters thereof, for example citric acid, malic acid, tartaric acid or tartaric acid diethyl ester, and zinc glycinate.

Odor Absorbers

Suitable odor absorbers are substances which are capable of absorbing and largely retaining the odor-forming compounds. They reduce the partial pressure of the individual components and thus also reduce the rate at which they spread. An important requirement in this regard is that perfumes must remain unimpaired. Odor absorbers are not active against bacteria. They contain, for example, a complex zinc salt of ricinoleic acid or special perfumes of largely neutral odor known to the expert as “fixateurs” such as, for example, extracts of ladanum or styrax or certain abietic acid derivatives as their principal component. Odor maskers are perfumes or perfume oils which, besides their odor-masking function, impart their particular perfume note to the deodorants.

Antiperspirants

Antiperspirants reduce perspiration and thus counteract underarm wetness and body odor by influencing the activity of the eccrine sweat glands.

Suitable astringent active principles of antiperspirants are, above all, salts of aluminium, zirconium or zinc. Suitable antihydrotic agents of this type are, for example, aluminium chloride, aluminium chlorohydrate, aluminium dichlorohydrate, aluminium sesquichlorohydrate and complex compounds thereof, for example with 1,2-propylene glycol, aluminium hydroxyallantoinate, aluminium chloride tartrate, aluminium zirconium trichlorohydrate, aluminium zirconium tetrachlorohydrate, aluminium zirconium pentachlorohydrate and complex compounds thereof, for example with amino acids, such as glycine.

Antidandruff Agents

Suitable antidandruff agents are piroctone olamine (1-hydroxy-4-methyl-6-(2,4,4-trimethylpentyl)-2-(1H)-pyridinone monoethanolamine salt), Baypival® (Climbazole), Ketoconazol® (4-acetyl-1-{4-[2-(2,4-dichlorophenyl) r-2-(1H-imidazol-1-ylmethyl)-1,3-dioxylan-c-4-ylmethoxy-phenyl}-piperazine, ketoconazole, elubiol, selenium disulfide, colloidal sulfur, sulfur polyethylene glycol sorbitan monooleate, sulfur ricinol polyethoxylate, sulfur tar distillate, salicylic acid (or in combination with hexachlorophene), undecylenic acid, monoethanolamide sulfosuccinate Na salt, Lamepon® UD (protein/undecylenic acid condensate), zinc pyrithione, aluminium pyrithione and magnesium pyrithione/dipyrithione magnesium sulfate.

Insect Repellents

Suitable insect repellents are N,N-diethyl-m-toluamide, pentane-1,2-diol or 3-(N-n-butyl-N-acetylamino)-propionic acid ethyl ester), which is marketed under the name of Insect Repellent® 3535 by Merck KGaA, and butyl acetylaminopropionate.

Self-Tanning Agents and Depigmenting Agents

A suitable self-tanning agent is dihydroxyacetone. Suitable tyrosine inhibitors which prevent the formation of melanin and are used in depigmenting agents are, for example, arbutin, ferulic acid, koji acid, coumaric acid and ascorbic acid (vitamin C).

Hydrotropes

In addition, hydrotropes, for example ethanol, isopropyl alcohol or polyols, may be used to improve flow behavior. Suitable polyols preferably contain 2 to 15 carbon atoms and at least two hydroxyl groups.

Preservatives

Suitable preservatives are, for example, phenoxyethanol, formaldehyde solution, parabens, pentanediol or sorbic acid and the silver complexes known under the name of Surfacine® and the other classes of compounds listed in Appendix 6, Parts A and B of the Kosmetikverordnung (“Cosmetics Directive”).

Perfume Oils and Aromas

Suitable perfume oils are mixtures of natural and synthetic perfumes. Natural perfumes include the extracts of blossoms, stems and leaves, fruits, fruit peel, roots, woods, herbs and grasses, needles and branches, resins and balsams. Animal raw materials, for example civet and beaver, and synthetic perfume compounds of the ester, ether, aldehyde, ketone, alcohol and hydrocarbon type may also be used.

Dyes

Suitable dyes are any of the substances suitable and approved for cosmetic purposes. Examples include cochineal red A (C.I. 16255), patent blue V (C.I. 42051), indigotin (C.I. 73015), chlorophyllin (C.I. 75810), quino-line yellow (C.I. 47005), titanium dioxide (C.I. 77891), indanthrene blue RS (C.I. 69800) and madder lake (C.I. 58000). These dyes are normally used in concentrations of 0.001 to 0.1% by weight, based on the mixture as a whole.

Process 1 relates to preparation of a concentrated solution which can be diluted to form the final product i.e. nanoemulsion. This provides cost advantage in terms of storage, display and transportation.

The inventors of the present invention have found out that the nano emulsion forms spontaneously without uses of high pressure homogenization and instrument alike

Further it was surprisingly found that mixing the component in appropriate combinations leads to the formation of nano emulsion without the use of high pressure homogenization, sonication, PIT, high temperature.

Eliminations of any one of the components or alteration of the composition leads to formation of cloudy or phase separated systems with higher (µm) size.
The oil-in-water nanoemulsion of the present invention forms very quickly with minimum requirement of equipment and skilled lab force. The present invention can be applied in the preparation of cosmetics or hair care, skin care formulations. The present invention can be used as a delivery system for cosmetics active ingredients such as lightening agents, darkening agents such as self-tanning agents, anti-acne agents, shine control agents, anti-microbial agents, anti-inflammatory agents, anti-aging agents, in particular anti-wrinkle agents, anti-mycotic agents, anti-parasite agents, external analgesics, sunscreens, photoprotectors, antioxidants, keratolytic agents, detergents/surfactants, moisturizers, nutrients, vitamins, energy enhancers, anti-perspiration agents, astringents, deodorants, hair removers, firming agents, anti-callous agents, and agents for hair, nail, and/or skin conditioning.

Nanoemulsion of the present invention can be used to make various cosmetic preparations including but not limited to facewash, shampoo, bodywash, shower gel, facial cleanser, leave on gel, conditioner, body conditioner, shaving gel/cream, after shave cream/gel, sunscreen, etc.

Preferred formulations are cleansing formulations such as facewash, shampoo, bodywash, shower gel, facial cleanser.

Another embodiment of the present invention provides a process for the preparation of the nanoemulsion of the present invention.

The nanoemulsion of the present invention is made by adding select mix of non-ionic surfactants to oils and water.

The non-ionic surfactants are selected form a group comprising: polyethylene glycol derivative of natural oils especially polyethylene glycol derivative of Ricinus communis (Castor) Oil, polyoxyethylene fatty acid ester of sorbitan especially polyoxyethylene sorbitan monolaurate, 2-Octyl-1-dodecan-1-ol and combinations thereof.

Illustrative examples suggest that in case non-ionic surfactants other than the stated non-ionic surfactants are used for the formation of nanoemulsion, the nanoemulsion of the present invention may not be formed by merely mixing and stirring.

Negative example are illustrated below using non-ionic surfactant other than the listed above namely; Sorbitan mono oleate, sorbitan mono stearate and Polyoxyethylene 2 stearyl ether.

The present invention is now illustrated by way of non-limiting examples.

Example -1: composition of the nanoemulsion (working example)

S. No Components % (w/w)
1 Water 50
2 Caprylic / capric triglycerides (oil) 6.6
3 Eutanol - G - 2-Octyl 1 dodecan 1-ol + TW-20 polyoxyethylene sorbitan monolaurate + PEG-40 Hydrogenated Castor oil (Non –ionic Surfactants) 43.4

Example-2 - wt/wt% of oil is greater than the predetermined range of the present invention. (non- working example)

S. No Components % (w/w)
1 Water 20
2 Caprylic / capric triglycerides (oil) 20
3 Eutanol - G - 2-Octyl 1 dodecan 1 ol + TW-20 polyoxyethylene sorbitan monolaurate + PEG-40 Hydrogenated Castor oil (Non –ionic Surfactants) 60

Observations: Nanoemulsion was not formed. Instead an opaque viscous milky gel was formed.

Example-3 - wt/wt% of surfactant is greater than the predetermined range of the present invention (non- working example)

S. No Components % (w/w)
1 Water 25
2 Caprylic / capric triglycerides (oil) 5
3 Eutanol - G - 2-Octyl 1 dodecan 1 ol + TW-20 polyoxyethylene sorbitan monolaurate + PEG-40 Hydrogenated Castor oil (Non –ionic Surfactants) 70

Observations: Nanoemulsion was not formed. Instead a transparent viscous gel was formed with transparency 95-99%.

Example-4 - wt/wt% of oil is lower than the predetermined range of the present invention (non- working example)

S. No Components % (w/w)
1 Water 60
2 Caprylic / capric triglycerides (oil) 3
3 Eutanol - G - 2-Octyl 1 dodecan 1 ol + TW-20 polyoxyethylene sorbitan monolaurate + PEG-40 Hydrogenated Castor oil (Non –ionic Surfactants) 37

Observations: Nanoemulsion was not formed. Instead a transparent solution was formed.

Example-5 - wt/wt% of surfactant is lower than the predetermined range of the present invention (non- working example)

S. No Components % (w/w)
1 Water 62
2 Caprylic / capric triglycerides (oil) 15
3 Eutanol - G - 2-Octyl 1 dodecan 1 ol + TW-20 polyoxyethylene sorbitan monolaurate + PEG-40 Hydrogenated Castor oil (Non –ionic Surfactants) 23

Observations: Nanoemulsion was not formed. Instead an opaque milk coloured solution was formed.

Example-6 - wt/wt% of water is greater than the predetermined range of the present invention (non- working example)

S. No Components % (w/w)
1 Water 68
2 Caprylic / capric triglycerides (oil) 6
3 Eutanol - G - 2-Octyl 1 dodecan 1 ol + TW-20 polyoxyethylene sorbitan monolaurate + PEG-40 Hydrogenated Castor oil (Non –ionic Surfactants) 26

Observations: Nanoemulsion was not formed. Instead an opaque milky solution was formed.

Example-7 - wt/wt% of water is lower than the predetermined range of the present invention (non- working example)

S. No Components % (w/w)
1 Water 18
2 Caprylic / capric triglycerides (oil) 15
3 Eutanol - G - 2-Octyl 1 dodecan 1 ol + TW-20 polyoxyethylene sorbitan monolaurate + PEG-40 Hydrogenated Castor oil (Non –ionic Surfactants) 67

Observations: Nanoemulsion was not formed. Instead a turbid solution was formed.

Example 8: Working / Positive example

S.No. Ingredient Wt%
1 Caprylic / Capric triglyceride (Oil) 6.8
2 Water 55
3 Polyoxyethylene sorbitan monolaurate 12.5
4 Polyethylene glycol hydrogenated castor oil 12.5
5 Eutanol-G 13.2

Observation: Nanoemulsion of the present invention was obtained.

Example 9: Negative examples where non-ionic surfactants other than those specified were used:

S.No. Ingredient Wt%
1 Caprylic / Capric triglyceride (Oil) 6.8
2 Water 55
3 Eutanol-G 12.5
4 Sorbitan mono oleate 25

Observation: Nanoemulsion of the present invention was not obtained; instead a milky gel was obtained.

Example 10: Negative examples where non-ionic surfactants other than those specified were used:

S.No. Ingredient Wt%
1 Caprylic / Capric triglyceride (Oil) 6.8
2 Water 55
3 Eutanol-G 12.5
4 sorbitan mono stearate 25

Observation: Nanoemulsion of the present invention was not obtained; instead a milky gel was obtained.

Example 11: Negative examples where non-ionic surfactants other than those specified were used:

S.No. Ingredient Wt%
1 Caprylic / Capric triglyceride (Oil) 6.8
2 Water 55
3 Eutanol-G 12.5
4 Polyoxyethylene 2 stearyl ether 25

Observation: Nanoemulsion of the present invention was not obtained; instead a milky gel was obtained.

Example 12: Process of preparation of the nanoemulsion

Step-1. Weigh 6.6 g Caprylic / capric triglycerides (oil) and 13.4 g Eutanol - G - 2-Octyl 1 dodecan 1 ol (surfactant) in a container.
Step-2. Weigh 15 g TW-20 polyoxyethylene sorbitan monolaurate (surfactant) in the mix as mentioned in step 1.
Step-3. Weigh 15 g of PEG-40 Hydrogenated Castor oil (surfactant) in the mixture as obtained in step 2 and mix with a stirrer at 3000-6000 RPM.
Step-4. Add 50 g water in the mixture as obtained in step 3 while stirring at 3000-6000 RPM until a thick transparent/translucent system was obtained.

Observations: A transparent/translucent nanoemulsion concentrate was formed, having particle size ranging from 15 - 150 nm. Transmittance of the system was 75%. 0.25 g of the nanoemulsion may be diluted with 50 g of water to form nanoemulsion of the present invention.