FORM - 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)
DETERGENT COMPOSITION
HINDUSTAN UNILEVER LIMITED, a company incorporated under
the Indian Companies Act, 1913 and having its registered office
at 165/166, Backbay Reclamation, Mumbai -400 020, Maharashtra, India
The following specification particularly describes the invention and the manner in which it is to be performed.

Field of the invention
The present invention is in the field of detergent compositions; in particular high active liquid detergent compositions, for use in laundry and/or household cleaning amongst others. The compositions of the present invention relate to the field of micro-emulsions, in particular water-in-oil micro-emulsions.
Background of the invention
Liquid detergent compositions are widely appreciated and preferred by many modern day consumers in both developed and developing and emerging markets. Such liquid detergent compositions are primarily used in Laundry and household care applications.
One of the most common problems is the removal of fatty stains and/or soil, especially solid or solidified fatty stains and/or soils. This is a problem in the field of household cleaning (e.g. kitchen surfaces, dish washing) and in the field of laundry and fabric washing (e.g. cuffs and collars). Especially tea, coffee, tomato (including tomato ketchup) and wine are known to pose cleaning difficulties on fabrics and surfaces alike.
Liquid detergent compositions are widely known in the art. Liquid detergent compositions generally comprise a surfactant active and a solvent. Liquid detergent compositions may further comprise perfume, builder, polymers, bleach, thickeners, fluorescers, and other common detergent ingredients. Liquid detergent compositions are often structured, e.g. to control the viscosity of the liquid or to improve stability and prevent phase separation or to be able to incorporate ingredients that are water insoluble. Present day liquid detergent compositions typically do not contain bleach and therefore do not work well on bleachable stains, such as coffee, tea, tomato and wine. At the same time,

current liquid detergent products contain only low levels of surfactant, and therefore also do not meet the consumers' requirement for the removal of oily and fatty stains.
One form of a stable liquid detergent composition is a detergent composition in the form of an emulsion. A defined kind of emulsion is the micro-emulsion. Generally emulsions are opaque liquids which are not appreciated by modern day consumers. Micro-emulsions can be made transparent and typically have a lower viscosity too.
WO95/27034 discloses detergent compositions in the form of oil in water micro-emulsions providing rapid stain removal. The composition of WO95/27034 comprises a surfactant system comprising short chain length non-ionic alcohol ethoxylates having less than 12 carbon atoms and with at least 45% of C10 material. It is found that these oil in water micro-emulsions do not provide adequate dissolution of fatty stains and soils when applied neat. Fast fat (or oily soil) solubilisation when applied neat onto a fatty stain or soil remains to be desired for amongst other the dissolution of sebum on shirt collars and fatty soils on hard surfaces.
Micro-emulsions have also been disclosed in a number of other documents such as US 5,415,812, which discloses a light duty detergent composition; or US 4,438,009, which discloses low solvent laundry pre-treatment compositions.
In EP-A2-610 010 bleach containing micro emulsions have been disclosed, however, this disclosure relates to a o/w (oil in water) microemulsion. As the continuous phase is aqueous, it's efficacy in solubilising fatty solids leaves to be desired.

To overcome the detrimental effects of bleach (e.g. PAP) in liquid detergent compositions, it has been proposed to encapsulate PAP in order to shield it from sensitive ingredients and to avoid degradation of the PAP. Especially in the field of mechanical dish washing, solutions of wax encapsulation have been proposed. However, the wax encapsulation required high temperatures to dissolve the coating and release the PAP. In low temperature washing and cleaning process such coatings will not dissolve. An alternative stabilisation system for PAP remains to be desired.
Other pre-treatment compositions have been proposed, mostly in the field of laundry and fabric cleaning, for providing stain removal.
In US 4,561,991 laundry pre-treatment compositions are disclosed in the form of micro-emulsions. It discloses mixtures of polyamines and grease cutting solvents. Other surfactants such as non-ionic surfactants are also disclosed.
What remains to be desired is a liquid detergent composition that removes soils and/or stains of solid or solidified fatty material in the main wash at neutral pH.
It is an object of the present invention to provide a composition that provides fast dissolution of solid fatty material.
It is a further object to provide a stable bleach containing liquid detergent composition.
It is another object of the invention to provide a stable concentrated detergent composition containing high levels of surfactant material.
It is another object of the invention to provide a transparent concentrated detergent composition.

It is another object of the invention to provide a concentrated detergent composition that shows fast dissolution in water.
It is yet another object of the invention to provide a concentrated detergent composition having a low viscosity.
It is yet another object of the invention to provide a liquid detergent composition that provides fast dissolution of oily/fatty stains or soil when applied neat.
Surprisingly it has been found that a water-in-oil micro-emulsion detergent composition comprising a hard water tolerant surfactant, water, oil and phtaloyl amino peroxycaproic acid) PAP provides a concentrated liquid bleaching detergent composition that removes soils and/or stains of solid or solidified fatty material in the main wash at neutral pH.
Summary of the invention
Accordingly the present invention provides a water-in-oil micro-emulsion detergent composition comprising 20-75% by weight of a surfactants system; 5-20% by weight of an aqueous solution having an ionic strength of 0.01 - 4 mol/L comprising: water; and an electrolyte, excluding surfactant system (a); 10-40 % by weight of a saturated oil; and 0.1-10% by weight of phtaloyl-amino-peroxycaproic acid (PAP); and wherein the composition comprises less than 100 ppb of transition metal ions, and wherein the pH is between 4 and 8.
In another aspect the invention provides a process for preparing a micro-emulsion according to any one of claims 1 to 9 comprising the steps in sequence of: adding in the surfactant system to a oil/solvent, mixing them together by an overhead stirrer, adding the PAP and mixing again; adding

optional hydrophobic ingredients, and adding aqueous phase containing electrolytes.
Although the examples in this application are predominantly showing laundry applications, it is noted that household cleaning applications, including hard surface cleaning applications, dishwashing, etc and fabric conditioning applications are also included in the scope of this application.
These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from a reading of the following detailed description and the appended claims. For the avoidance of doubt, any feature of one aspect of the present invention may be utilised in any other aspect of the invention. The word "comprising" is intended to mean "including" but not necessarily "consisting of or "composed of." In other words, the listed steps or options need not be exhaustive. It is noted that the examples given in the description below are intended to clarify the invention and are not intended to limit the invention to those examples per se. Similarly, all percentages are weight/weight percentages unless otherwise indicated. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word "about". Numerical ranges expressed in the format "from x to y" are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format "from x to y", it is understood that all ranges combining the different endpoints are also contemplated.
Detailed description
The invention relates to water-in-oil (w/o) micro-emulsion detergent composition.

Water-in-oil micro-emulsion
A water-in-oil micro-emulsion has a configuration comprising discrete droplets of water in oil. These w/o microemulsions are also characterised by a low electrical conductivity values, preferably < 1 mS/cm, more preferably < 0.1 mS/cm, (e.g. measured with a conductivity meter; (e.g. Orion 150)}. In addition, the water volume fraction in the microemulsion is typically < 0.2, to avoid percolation of water droplets leading to a higher electrical conductivity of the sample. Typical water droplet diameters are in the range of 2 - 50 nm (e.g. measured by dynamic light scattering technique by a Brookhaven goniometer system, equipped with a laser and photo detector and an auto-correlator). Typically, the viscosity is in the range of 30 - 300 CP (measured at 20 sec-1, using a controlled stress rheometer, CSL 500 TA Instruments).
Surfactant
The compositions according to the invention typically comprise 20 to 75% by
weight of the composition of a surfactant.
Hard water tolerant surfactants, such as alkyl ether sulphates (e.g. SLES), Alkyl polyether carboxylates, esters and amides of fatty acids, alkane sulphonates, Polyoxyalkylene phosphate esters, phosphated and polyphosphated alcohols, sulfosuccinates (di-2-ethylhexyl sulfosuccinates) alkoxylated non-ionic surfactants (e.g., lauryl alcohol ethoxymers), EO/PO block copolymers, Alkyl polyglucosides (APGs), Alkyl N-methyl glucamides, Amine oxides, Amine ethoxylates, Methyl ester ethoxylates, alkanol amides, Amidopropyl amines, carboxybetaines, Sulfo- and phosphor-betaines, Amtnoethylethanolamine-derived amphoterics (alkyl amphomonopropionates).
The most preferred hard water tolerant surfactants are alkoxylated non-ionic surfactants, Alkyl ether sulfates, Alkyl polyglucosides and mixtures thereof.

The surfactant is preferably present in a concentration of at least 30%, more preferably at least 40%, still more preferably at least 50%, or even at least 60% by weight of the composition. The surfactant is preferably present in a concentration of not more than less than 70% by weight of the composition.
More suitable hard water tolerant surfactants may be found in well known textbooks like "Surface Active Agents" Vol. 1, by Schwartz & Perry, Interscience 1949, Vol. 2 by Schwartz, Perry & Berch, Interscience 1958, and/or the current edition of "McCutcheon's Emulsifiers and Detergents" published by Manufacturing Confectioners Company or in "Tenside-Taschenbuch", H. Stache, 2nd Edn., Carl Hauser Verlag, 1981.
In laundry and fabric cleaning compositions, anionic and non-ionic surfactants are most preferred, while any surfactant may be used in household cleaning compositions.
The linear or branched aikoxylated fatty alcohol, having a carbon chain of between 10 and 16 carbon atoms are preferred in the composition. The fatty alcohol is preferably ethoxylated, having an average of between 0 and 7 EO groups.
For a dish washing liquids, anionic and non-ionic surfactants, and combinations are the most preferred. For hard surface spray cleaner (spray and wipe) any surfactant may be used.
High active compositions, even preferably comprise at least 50% by weight, more preferably at least 60% by weight or even at least 70% by weight of the surfactant system.

Other liquid laundry or fabric cleaning compositions, fabric conditioning compositions and household cleaning compositions (e.g. dishwashing compositions) typically comprise not more than 75% by weight, more preferably not more than 70% by weight, still more preferably not more than 60% by weight, or even not more than 50% by weight.
Aqueous solution
The composition comprises 5-20% by weight of an aqueous solution, having an ionic strength of from 0.01 to 4 mol/l, preferably at least 0.05 mol/l, preferably at least 0.1 mol/l, preferably at least 0.2 mol/l, or even at least 0.5 mol/l, but preferably not more than 3.5 mol/l, or even not more than 3 mol/l.
The aqueous composition comprises water and an electrolyte for improved performance.
The electrolyte is typically present in the composition in such a concentration that the ionic strength is in the above given range. Typically the electrolyte is present in a concentration of up to 15 % by weight based on the aqueous solution, when the electrolyte is a mono-valent electrolyte salt. The required amount is dependent on the type of electrolyte used and its valance. Without wishing to be bound by a theory, it is found that the electrolyte requirement follows the Schulze-Hardy rule for colloidal solutions, which defines the amount needed on the bases of the required concentration of a monovalent cation divided by the (valence)6; for example, when 15% of Na2S04 would be required to form a micro-emulsion, it could be replaced by CaSCU in a concentration of about 15%/26=15%/64=0.23%.
Following the above equation, monovalent cationic salt are preferably present in a concentration of between 1 and 15% based on the aqueous solution, while divalent cationic salt are preferably present in a concentration of between 0.01

and 4% based on the aqueous solution, and trivalent and multivalent cationic salt are preferably present in a concentration of between 0.005 and 2% based on the aqueous solution.
Preferred electrolytes are phosphates, sulphates of alkali metal and alkaline earth metals mixtures of any of the above.
Preferred trivalent metal cation is Al3+. However, transition metal cations are excluded as they are detrimental to bleach stability.
Hydroxide salts are not preferred, due to unfavourable pH effects and undesirable reactions.
Saturated oil
The composition further comprises 10 to 40% by weight of a saturated oil. The oil is a saturated, linear, branched or cyclic hydrocarbon with MP >-100 °C , selected from the following class of chemicals: (i) esters; (ii) acids and (iii) triglycerides and (iv) alkanes. The oil preferably has a a Hansen solubility of between 14 and 20 (MPa)0"5. The Hansen solubility is preferably at least 15 (MPa)05, more preferably at least 16 (MPa)0.5, and typically not more than 19 (MPa)05 or even not more than 18 (MPa)05.
The oil preferably has a solubility of solid triglyceride fatty matter into the oil and/or solvent of more than 3% by weight. Preferably the solubility of solid trilaurin (a triglyceride) fatty matter into the oil is more than 5%, or even more than 10%. This percentage is based on the aggregate amount of the oil and the trilaurin dissolved therein.

The oil is preferably selected from alkyl-, aryl- esters of saturated fatty acids saturated fatty acid oils, mono- di- and tri-glycerides without any unsaturations, sugar derived polyesters and sucrose polyesters,.
Preferred alkyl- fatty acid esters have a chemical structure of R2-COO-R1, where R2 = C7-C22 and R1 = C1 - C22. . Preferred fatty acids are C8-22 fatty acids and including di- and tri-carboxylic acids and oligomeric fatty acids (such as commercially available as Pripol 1017 ex. Unichema). Preferred triglycerides include those of medium chain glycerides, which are liquid at ambient conditions are also contemplated.
It is especially preferred to use oils from renewable sources, such as oil derived from palms, soy, coconut and jatropha.
Combinations of any of the oils are also included in the scope of this invention.
phtaloyl-amino-peroxycaproic acid
The bleach according to the invention is phtaloyl-amino-peroxycaproic acid (also referred to in literature as N-N-phtaloyl-amino-peroxycaproic acid, phthalimido perhexanoic acid or simply as PAP) is an oil soluble organic peracid and it is typically incorporated in to the composition up to 10 % by weight, preferably up to 8% by weight, more preferably up to 5% by weight; but is typically persent in a concentration of at least 0.1%, more preferably at least 0.5% still more preferably at least 1%, or even at least 2% by weight of the composition.
The PAP is preferably solubilised in the oil/solvent phase of the water-in-oil micro-emulsion. It is expected that the PAP acts on soil during the interaction of oil droplets with the soiled substrates. The pH of the composition is acidic to neutral, by which is meant that the pH is between 4 and 8. The best results with

compositions wherein PAP is incorporated, are obtained when the pH is in the range of 5 to 7.
Optional ingredients
The composition may further comprise builder, anti-redeposition agents, mosquito and/or insect repellents, shading dyes, antimicrobial agents (oil based), oil-soluble fluorescer, enzymes, perfumes and soil release polymers.
Perfume may be incorporated in the composition in a concentration of between 0.1 and 5% by weight. Typically the concentration is less than 3%, even less than 2%; generally the perfume is present in a concentration of between 0.5 and 1% by weight. It is demonstrated that perfume incorporated in a micro-emulsion provides up to 10 times better deposition on fabrics and the perfume remains for a longer period compared to only surfactant solution containing equivalent amount of perfume.
Viscosity
The viscosity of the composition is preferably low. By low is meant not more than 1000 mPa.s, more preferably not more than 500 mPa.s, preferably less than 300 mPa.s, still more preferably less than 200 mPa.s, or even less than 150 mPa.s. It is preferred that the composition has a viscosity of more than 5 mPa.s, more preferably more than 10 mPa.s, still more preferably more than 20 mPa.s or even more than 50 mPa.s. All viscosities mentioned are measured by a Cammed CSL-500 rheometer with standard cone and plate geometry, at 20 sec"1 and 25°C.

pH
The pH is preferably around neutral in a range of 4 to 8, preferably at least 5 and not more than 7. Any known pH adjustment agents or buffer may be used when required.
Process
The micro-emulsion is preferably made by adding in sequence the surfactant system to a oil/solvent, mixing them together by an overhead stirrer, adding optional hydrophobic ingredients such as fluorecser, bleach and essential oils/perfumes; adding aqueous phase containing electrolytes and adding enzymes/bleaches.
Optional hydrophobic ingredients include fluorescer, perfume and water insoluble soil release polymers (e.g. gerol, trademark ex Rhodia).
Product format
The laundry product may be packaged in a standard bottle. Pre-spotting products are typically filled into a dispensing device, such as, stain pens, roller balls, brush pens, and/or spays dispensers (e.g. trigger spray dispensers or squeeze bottles). Household cleaning products are typically in the form of trigger sprays. Dishwashing liquids are typically sold in bottles.
Description of the Figure
Figure 1 is a ternary diagram showing the different forms of mixtures of surfactant (C12E07 = NI surfactant, (Galaxy 257), ex Galaxy, India), water (H20) and oil (MD = Methyl Decanoate). The diagram shows the different kinds

of liquids/emulsions that may be obtained and the preferred region (shaded area) of the water in oil microemulsion (W/O-ME) on the right.
In the figure La stands for Liquid Crystalline phases, L2 stands for Reversed Micellar Phases, L1 stands for Micellar Phases and uE stands for Microemulsion.
Examples
The invention will now be illustrated by means of the following non-limiting
examples.
Example 1: preparation of PAP containing micro-emulsions The PAP may be obtained in pure form or obtained by suspending commercially available 17%w PAP suspension in water using stabilisers and structurants (ex Solvay, Italy), followed by extraction of PAP from the commercial source by using chloroform. The percentage purity of the extracted PAP is 90-92 %w.
The required amount of the oil is weighed and 1-4 %wt of pure or purified PAP is mixed with the oil. Non-ionic surfactant (e.g. Galaxy 257 (C12-15E0<7>)) is then added and the mixture is stirred until a clear solution is obtained.
De-ionised water is added and shaken well to get the required formulation. The composition of the formulation is chosen from the phase regions, given in the ternary diagram (see Figure 1).
Some examples of compositions according to the invention are given in the table below.

Table 1: Compositions

1 2 3 4 A
Chemical %w %w %w %w %w
C12E07 (Alcohol Ethoxylate) 70 70 59 70 73
Methyl decanoate 13 18 20 12.8 13.5
Water 13 8 20 12.8 13.5
PAP (90-92% pure) 4 4 1 4
Na2S04 (electrolyte) 0.4
The table above shows 3 compositions according to the invention (compositions 1 - 3) and a comparative composition (composition A).
Example 2: PAP stability
It is known in the art that PAP is not stable in aqueous compositions, while it is reasonably stable in organic solvents. The PAP stability in microemulsion compositions comprising water is yet to be determined.
The level of PAP in the product is determined by the titration under acidic conditions against thiosulfate/KI according to the following method.
Method of analysis of PAP in the formulation by iodometric titration:
A known quantity (g) of the liquid prototype containing PAP is taken. 30ml of
iso-propanol is added to dissolve the contents. Later on, 50ml of deionised (Dl)
water is added, followed by 20 ml of glacial acetic acid. The mixture is stirred
well. 3 g of potassium iodide (Kl) salt is weighed and added to the solution
mixture.

The oxygen liberated from PAP, oxidizes iodide (I) to l2. This liberated iodine is estimated using standardized sodium thiosulfate solution, which directly corresponds to the amount of PAP initially present in the solution.
The reaction involved in the above procedure is;
2PAP → 2PAC + 02
02 + 21" + 2H+ → l2 + H20
l2 + 2Na2S2O4 → 2Na2S406 + Na++ I
The PAP concentration can then be calculated by the following equation:

Wherein:
V (ml) = Volume of thio required to reduce the Iodine liberated
N = Normality of thio solution used for the analysis
W = Weight of the sample taken for analysis
277/2 = Equivalent weight of PAP
PAP incorporated in the oil alone
About 0.82% by wt. PAP incorporated in the oil mentioned showed stability for
30 days with 6% degradation in PAP concentration.
PAP in the composition
The PAP micro-emulsion of composition 1 was used and stored for over 2 months. Samples were taken according to table 2 and analysed as indicated above. The results are shown in table 2 below.

Table 2: PAP microemulsion degradation

Days PAP concentration (%wt)
0 3.69
3 3.26
10 2.65
18 2.23
25 2.27
31 1.54
67 0.76
The PAP degradation follows a first order reaction kinetics with half life of about 30 days.
Example 3: Washing experiment with PAP containing bleach formulation: Washing tests were done with WFK cotton, polycotton (polyester-cotton blend) and polyester fabrics were stained with black tea and grass.
0.5ml of the black tea (without milk) brewed with a Taj Mahal tea bag (ex Hindustan Unilever Ltd, India) and 0.5 ml of the grass extract, obtained by grinding fresh grass with water (1:2 by wt.) in mixer, were used to stain the fabric test swatches.
The formulations with PAP (composition 1) and without PAP (comparative composition A) were directly applied on to the fabric on equal active basis that could sufficiently cover the stain spot area. After leaving it in air for two minutes, the fabrics were soaked in 24 °FH water at 25 °C for 30 min and then washed in a terg-o-tometer (7243 Es) for 15 min, followed by rinsing for two min two times. The L/C was maintained at 20 and spindle rpm at 80-90.

Reflectance was measured with a reflectometer (Macbeth spectrophotometer -Colour eye 7000A) before and after the wash process, at 460 nm. This difference is commonly referred to in the industry as dR460. the higher the dR460 value, the better the cleaning performance. The experiment is repeated in triplicate and the standard deviations (SD) are calculated. The results are found in the table below.
Table 3a: Tea stains results

Comp A Comp 1
dR460 SD dR460 SD
Cotton 22.345 0.684 30.904 1.398
Poly cotton 32.638 0.740 35.943 0.624
Polyester 36.375 0.631 42.643 1.230
Table 3b: Grass stains results

Comp A Comp 1
dR460 SD dR460 SD
Cotton 27.346 0.467 31.785 0.346
Polycotton 24.133 3.111 34.144 0.686
Polyester 36.035 2.444 38.801 0.556
The results in tables 3a and 3b show superior cleaning with the PAP containing micro-emulsion as compared to a regular micro emulsion.

Claims
1 Water-in-oil micro-emulsion detergent composition comprising
a 20-75% by weight of a surfactants system;
b 5-20% by weight of an aqueous solution having an ionic strength of
0.01 - 4 mol/L comprising:
i water; and
ii an electrolyte, excluding surfactant system (a) c 10-40 % by weight of a saturated oil; and
d 0.1 -10% by weight of phtaloyl-amino-peroxycaproic acid (PAP); and wherein the composition comprises less than 100 ppb of transition metal ions, and wherein the pH is between 4 and 8.
2 A composition according to claim 1, wherein the saturated oil is selected from fatty acid esters, fatty acid oils, tri-glycerides, sugar derived polyesters and sucrose polyesters and mixtures thereof.
3 A composition according to any one of claims 1 or 2, wherein the oil has a Hansen solubility of between 14 and 20 (MPa)0.5.
4 A composition according to claim 3, wherein the Hansen solubility is between 16 and 18MPa0.5.
5 A composition according to anyone of claims 3 or 4, wherein the solubility of solid trilaurin fatty matter into the oil of more than 3% by weight;
6 A composition according to any one of the preceding wherein the aqueous solution has an ionic strength of 0. 1 - 4 mol/l.

7 A composition according to any one of the preceding claims, further comprising a perfume.
8 A trigger spray dispenser comprising the composition according to any one of claims 1 to 7.
9 A stain pre-spotter device selected from stain pens, roller balls and brush pens, comprising the composition according to any one of claims 1 to 7.
10 Process for preparing a micro-emulsion according to any one of claims 1 to 7 comprising the steps in sequence of:
a adding in the surfactant system to a oil/solvent,
b mixing them together by an overhead stirrer,
c adding the PAP and mixing again,
d adding optional hydrophobic ingredients
e adding aqueous phase containing electrolytes.