Background and Prior Art Hard surfaces within the household, such as those found in kitchens and bathrooms (and the utensils, appliances, fixtures and fittings contained therein) are prone to contamination with various types of soil. Kitchen surfaces are especially prone to contamination with tough and difficult to remove soil consisting of dried-on or cooked-on food. The problem becomes more pronounced when the soil builds on over a period of time and this requires considerable effort to clean.

Solvent based compositions are well known for cleaning hard surfaces which are difficult to clean. EP 0 428 816 and EP 0 261 874 disclose solvent based hard surface cleaning compositions using different water miscible or water soluble solvents and surfactants.

US 5 780 407 discloses a non-aqueous cleaning composition which contains at least two different surfactants, which have a significant difference in their HLB values, along with a

diluent oil. This is used for cleaning crude oil and lifting oil from surfaces.

US 5 080 822 discloses a stable aqueous degreaser composition in the form of an aqueous solution comprising at least one sparingly water soluble organic solvent, an organic solubilizing coupler required to completely solubilize the organic solvent and water.

Removal of tough polymerised oil films is typically done by the abrasives which are present in dish wash powders and bars. When clear liquids are used for dish washing, the abrasive action required for removing tough solid films is provided by abrasive implements. However the use of abrasive products or abrasive implements leaves visible scratches on the surfaces being treated. This leads to a gradual loss of shine or decay of appearance, which is currently accepted by the consumers as a necessary"cost"for having clean surfaces.

There remains a need for a product which cleans tough soil films without degrading the appearance of kitchen surfaces and kitchen utensils.

Summary of the Invention According to the present invention there is provided a cleaning composition comprising: (i) a first liquid phase comprising one or more liquids having an electric dipole moment of less than 1.85 debye, (ii) a second liquid phase comprising one or more liquids having an electric dipole moment of 1.85 debye or more; in which the liquids are present at levels above their mutual miscibility limits, such that they form at least two immiscible phases, and in which at least 10% of the first liquid phase (by weight based on total weight of the first liquid phase) has an electric dipole moment less than 1.85 debye but greater than 0.8 debye.

The composition of the invention has been shown to remove tough or polymerised soil more effectively from hard surfaces than pure solvent cleaning or prior art cleaning compositions. Advantageously the composition of the invention does not require the incorporation of harsh abrasives or high levels of surfactant, and so is gentler and less damaging towards the surfaces being treated, as compared to the traditional cleaning methods and compositions of the prior art.

Detailed Description and Preferred Embodiments Electric dipole moment is property of a molecule and it reflects the extent of separation of charge centres in an electrically neutral molecule (Handbook of chemistry and

physics, CRC Press 80th Edition, Ed. David Lide). It is quantitatively expressed as the charge of the dipole times the distance of separation between the dipoles. It is expressed in debye. A dipole formed by a pair of poles with charge equal to 1 electronic charge unit (-1. 6 * 10-19 Coulombs) separated by a distance of 0.21 A°, has a dipole moment of 1 debye.

According to a preferred aspect of the present invention, at least 10% of the first liquid phase (by weight based on total weight of the first liquid phase) has an electric dipole moment in the range from 1 to 1.8 debye.

More preferably at least 50% of the first liquid phase (by weight based on total weight of the first liquid phase) has an electric dipole moment in the range from 1 to 1.8 debye.

Most preferably 100% of the first liquid phase (by weight based on total weight of the first liquid phase) has an electric dipole moment less than 1.85 debye but greater than 0.8 debye, preferably in the range from 1 to 1.8 debye.

This has been found to improve the rate of cleaning obtained with the composition of the invention.

The at least two immiscible phases formed by the composition of the invention exhibit at least one interface and the interfacial tension is preferably less than 45 mN/m.

Although it is not essential to incorporate surfactants, up to 10% surfactant (by weight based on the total weight of the composition) can form a part of the composition. When

surfactants are present the immiscible phases may form a stable emulsion. This emulsion may appear as a single homogenous system but actually comprises a stable dispersion of the immiscible phases.

First liquid phase The first liquid phase comprises one or more liquids having an electric dipole moment of less than 1.85 debye, and therefore can comprise liquids having a dipole moment ranging from 0 to less than 1.85 debye. However, at least 10% of the first liquid phase comprises liquids with an electric dipole moment less than 1.85 debye but greater than 0.8 debye, preferably from 1.0 to 1.8 debye.

The liquids for the first liquid phase may suitably be selected from hydrocarbons having a carbon chain length greater than 6, such as branched and linear alkanes of chemical formula CnH zon+2 where n is greater than 6. Examples include hexane, heptane, octane, nonane, decane, dodecance, tridecane, tetradecane, pentadecane and mixtures thereof.

Commercially available mixtures of this type include Isopar L (Cn-Cis alkanes, ex. Exxon) and DF2000 (ex. Exxon).

Also suitable are branched and linear alkenes with greater than 6 carbon atoms and with one or more degrees of unsaturation, such as octenes, nonenes, decenes, undecenes and dodecenes and mixtures thereof.

Also suitable are ethers including fluoroethers such as methoxy nonafluorobutane HFE-7100 (of formula C4F9-OCH3) and

ethoxy nonafluorobutane HFE-7200 (of formula C4Fg-OC2H5), esters, such as dibutyl phthalate and dioctyl phthalate, terpenes, such as limonene, and mixtures thereof.

Halogenated hydrocarbons such as carbon tetrachloride may also be used.

Also suitable are linear and cyclic silicone fluids having greater than 3 siloxane (SiO) units. Examples of suitable materials include octamethyl cyclotetrasiloxane, decamethyl cyclopentasiloxane, dodecamethylcyclohexasiloxane, decamethyltetrasiloxane, dodecamethyl pentasiloxane and mixtures thereof.

Liquids for the first liquid phase having an electric dipole moment less than 1.85 debye but greater than 0.8 debye may suitably be selected from chlorinated hydrocarbons such as dichloroethanes, dichloroethylenes, dichloroethylethers, dichloromethane, dichloropropanes, and chloroform. Other halocarbons such as dibromomethane, bromochloromethane and bromoform may also be suitable.

Also suitable are ethylene glycol, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, ethylene glycol ethyl ether acetate, ethylene glycol monomethyl ether acetate, ethyl acetate and ethyl formate.

Also suitable are alcohols, which show limited water miscibility such as butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol and all compounds described by the generic formula CnH 2n+20 and their isomers.

Second liquid phase The second liquid phase may suitably be selected from water and water soluble solvents such as acetone, alkanolamines, water miscible alcohols and ethers, and mixtures thereof.

Most preferably the second liquid phase consists of water.

Conventional ingredients It is possible to incorporate other conventional detergent ingredients such as surfactants, builders, soil release polymers, hydrotropes, enzymes, bleaches, and perfumes into the composition of the invention. They may be suitably incorporated into the first or second liquid phases.

Detergent actives The composition according to the invention may optionally comprise an anionic surfactant. Other detergent actives such as nonionic, cationic, amphoteric or zwitterionic surfactants may also be present. It is preferred that a detergent active is incorporated in the composition up to a maximum concentration of 10% by weight based on the total weight of the composition.

Examples of suitable detergent actives are those compounds commonly used as surface-active agents given in the well- known textbooks"Surface Active Agents", Volume I by Schwartz and Perry and"Surface Active Agents and Detergents", Volume II by Schwartz, Perry and Berch.

The invention will now be illustrated by the following non- limiting Examples, in which all parts are by weight based on total weight unless otherwise specified.

EXAMPLES Process for preparing the composition: 50ml of the first liquid phase (water) was taken in a glass beaker to which 50ml of the second liquid phase was added drop wise to the first liquid phase under constant stirring.

In cases where the second liquid phase was made up of two liquids, those liquids were combined prior to adding dropwise to the first liquid phase.

In example 11,0. 5% by wt. of sodium linear alkyl benzene sulphonate was dissolved in the first liquid phase (water), and the second liquid phase (a combination of hexadecane and chloroform) was added drop wise to the first liquid phase under constant stirring. This formed a stable milky white emulsion.

Comparison formulations: Compositions with two liquid components used as controls for comparison of the performance were prepared by the same process of dropwise addition with strirring as described above. Single phase systems were used as such.

Method of depositing the soil and cleaning Stainless steel plates were coated with sunflower oil, and the oil coating polymerised by heating the plates in an oven maintained at 180° C for 1 hr. The plates coated with the polymerised oil were soaked in 100ml of the liquid cleaning compositions described in Table 1 and Table 2, for 5 minutes to 60 minutes. The plates were gently agitated. The plates were removed after fixed time intervals and washed under a tap of running water for about 30 seconds. A comparison of the initial level of the polymerised soil deposited on the plate was compared by a quantitative optical technique, with the removal of the soil after cleaning and washing. The data was collected in replicates.

Table 1 Dipole Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Ex 6 Ex 7 Ex 8 Ex 9 Mo. D Water 1.85 100 50 50 - 50 - 50 - 50 Hexadecane 0 - 50 - 100 - - - - - Xylene 0.64 - - 50 - - - - - - Chloroform 1.04 - - - - 50 100 - - - Isopropanol 1.56 - - - - - - - - 50 Isobutanol 1.64 - - - - - - 50 100 - Immiscible phases - yes yes - yes - yes - No % Clean - 5min 0 0 0 0 100 0 50 0 0 % Clean - 60min 0 0 0 0 100 0 100 0 0

The data in Table 1 shows that when plates soiled with polymerised oil, created in the manner described above, are washed in a polar liquid (water) alone, there is no removal of soil (Ex 1). Similarly when they are washed in equal volumes of water and a less polar liquid, for example hexadecane (Ex 2) or xylene (Ex 3) or in a less polar system alone (Ex 4), where no fraction of the less polar liquid has a dipole moment above 0.8 debye, there is no removal of soil. However, example 5 shows that if the less polar liquid phase used has a dipole moment above 0.8 debye and is used along with a first, more polar, liquid phase (water), , and the two liquids are present above their mutual miscibility limits, complete removal of the tough soil occurs. Example 6 shows that when the less polar liquid phase having a dipole moment above 0.8 debye is used without the more polar phase, no cleaning occurs. Example 7 shows that where the less polar liquid phase (isobutanol) has a dipole moment of 1.64, and is used in combination with a more polar liquid (water) above their mutual miscibility limit, complete soil removal is achieved. Example 8 shows that isobutanol alone, is ineffective. In example 9, although the dipole moment of isopropanol is greater than 0.8 debye, it is miscible with the more polar phase water.

The resulting composition is ineffective in cleaning. It may be noted that in example 5 the less polar liquid phase is heavier than the more polar liquid phase, while in example 7, the more polar liquid phase is heavier. This shows that the relative densities of the liquids do not effect cleaning.

The effect of surfactants in the system The data shown in this table compares two compositions, both in accordance with the invention, but different in that one contains surfactant (Ex 11) while the other does not (Ex 10). In the example 11 where 0.5% surfactant was added, the less polar liquid phase with dipole moment less than 0.8 debye (Hexadecane) was proportionately reduced.

Table 2 Dipole moment Ex 10 Exll (D) Water 50 50 Hexadecane 0 23.3 22.8 Chloroform 1.04 26.7 26.7 Surfactant NaLAS 0 0. 5 % Clean-5min 45 70 % Clean-60min 100 100

Example 10 shows that only a fraction of the less polar liquid phase needs to have a dipole moment above 0.8 debye for effective cleaning. It can be seen from example 11, that while the presence of surfactant is not an essential part of this invention, it is not a deterrent and aids the cleaning process, hence forming a preferred option. It is also evident from table 1 and 2 that if the less polar phase consists entirely of a liquid with dipole moment greater than 0.8 debye the rate of cleaning is faster.