HUP0000687A2 - Aqueous cleaning agent for solid surfaces, as well as a process for cleaning solid surfaces - Google Patents

Abstract

The water purifiers according to the invention for cleaning solid surfaces contain a mixture of surfactants, from which the mixture of surfactants is diluted to the total amount of surfactants a) at least 65% by weight of non-ionic surfactants, b) less than 1% by weight of anionic surfactants and c) 0.1-35% by weight of cationic surfactants surfactant, which is a mineral aliphatic quaternary alkyl ammonium compound, of which the alkyl chain contains at least 10% by weight of 18-26-carbon alkyl pipe powder, of which the cleaning agent also contains at least 0.5% by weight of an organic amine with a pKa value of at least 8.0. The scope of the invention also includes a method for cleaning solid surfaces, in which the surface is treated with the above cleaning agent, and this cleaning agent is powdered on the surface. ŕ

Description

PooöotoS?

KCU YEAR 3K

Aqueous cleaning agents for solid surfaces and process

for cleaning solid surfaces

The invention relates to a cleaning agent for solid surfaces, which has an alkaline pH and contains a cationic surfactant of the aliphatic alkyl compound type and a nonionic surfactant.

Conventional cleaning of hard surfaces such as wood, glazed tiles and painted metal involves removing soil with surfactants or solvent-based preparations and then applying a varnish, wax or polish in a separate step to seal and protect the surface and to reduce the rate of soil re-deposition. This two-step cleaning and sealing process is time-consuming and complicated.

To provide secondary cleaning benefits, it has been proposed to incorporate a number of soil release agents into cleaning compositions, including polymers, siloxanes, and cationic surfactants of the dialkyl quaternary type. These soil release agents are believed to act by depositing a layer of polymer, siloxane, or surfactant on the surface during cleaning. The deposited layer is believed to be beneficial for subsequent cleaning operations by reducing soil adhesion to the surface.

To facilitate cleaning, the compositions described are preferably strongly alkaline. The cheapest of such materials are quaternary cationic surfactants. These quaternary salts generally contain a quaternary nitrogen atom to which one or two aliphatic alkyl groups are attached.

PCT/EP97/07152 chain and three or two short alkyl chains. In the case of compositions containing cationic surfactants of the quaternary dialkyl compound type, difficulties arise in stabilizing the products against flocculation and/or preventing phase separation due to the interaction between the components present.

Accordingly, there is a technical difficulty in stably formulating detergents containing an effective amount of a highly alkaline, quaternary nitrogen-containing soil-releasing agent.

We have developed formulations containing a stable, alkaline organic amine that cleans the treated surface and then deposits a layer of a relatively long chain monoaliphatic alkyl cationic surfactant on it, which facilitates the removal of subsequent soiling on the surface. We believe that the stability of these formulations is due to the combination of the alkaline organic amine and the monoaliphatic alkyl cationic surfactant.

Based on the above, the invention provides aqueous cleaning compositions for solid surfaces, which comprise a mixture of surfactants, wherein the mixture of surfactants, based on the total amount of surfactants, comprises a) at least 65% by weight of nonionic surfactant, b) less than 1% by weight of anionic surfactant and c) 0.1-35% by weight of cationic surfactant, which is a monoaliphatic quaternary alkyl ammonium compound, wherein the alkyl

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PCT/EP97/07152 contains at least 10% by weight of alkyl groups having 18-26 carbon atoms in the chain, wherein the cleaning agent further contains at least 0.5% by weight of an organic amine having a pK _a value of at least 8.0.

The cationic surfactants present in the cleaning compositions of the invention are believed to modify the surface energy of the surfaces treated with them and thereby increase the contact angle of the soil subsequently detached from the modified surface.

To further illustrate the invention, it is discussed in detail below, with particular reference to the preferred ingredients and details of the formulation of the compositions.

Cationic surfactants

A variety of cationic monoaliphatic quaternary alkyl ammonium compounds can be used in the compositions of the invention. Particularly suitable cationic surfactants are the compounds of formula (I),

[R1R2R3R4N] x (i) wherein R _n R ₂ and R ₃ are independently alkyl groups having 1-6 carbon atoms, R ₄ is aliphatic alkyl group, and X is a monovalent anion, wherein the distribution of the carbon chain lengths is such that at least 10% by weight of the compound contains aliphatic alkyl groups having 18-26 carbon atoms. Preferably, less than 60% by weight of the compound is a monoaliphatic quaternary alkyl ammonium compound containing aliphatic alkyl chains having 16 carbon atoms or less.

In terms of secondary purification benefits, these longer chain monoaliphatic quaternary alkyl compounds are likely to be more suitable than shorter chain monoaliphatic

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PCT/EP97/07152 ··· · · alkyl compounds. It has also been found that the use of monoaliphatic alkyl compounds provides a wider scope for formulation than the corresponding aliphatic dialkyl compounds. Halide ions, in particular chloride or bromide ions, prove to be suitable counterions.

Aliphatic alkyl compounds can be derived from synthetic or natural raw materials. When aliphatic alkyl compounds are derived from natural raw materials, they are generally mixtures of compounds containing alkyl groups in the aliphatic alkyl chain region. The alkyl groups in the above compounds are preferably fully saturated. In accordance with the objective, saturated alkyl chains exhibit effective properties due to the fact that the alkyl chains provide better coverage at surfaces and interfaces.

The cationic surfactant preferably comprises a cation of the above formula, wherein R1, _R2 and _R3 are methyl groups. Commercially available materials from natural sources in which methyl groups are substituted for lower alkyl groups are available.

A particularly preferred compound is trimethylbehenyl ammonium bromide. It has been found that this compound flakes over time in the presence of significant amounts of inorganic salts, including alkali metal compounds such as sodium hydroxide and sodium or potassium carbonate. The compositions of the present invention, as described hereinafter, avoid this difficulty.

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Nonionic surfactants

It is essential that the compositions of the invention contain a nonionic surfactant. The presence of a nonionic surfactant contributes substantially to the cleaning effect of the compositions of the invention.

Suitable nonionic surfactants can be broadly described as condensation products of alkylene oxide groups of hydrophilic nature with organic hydrophobic compounds of aliphatic or alkylaromatic nature.

The length of the hydrophilic or polyoxyalkylene group to be condensed with any given hydrophobic group can be readily determined to achieve a water-soluble compound exhibiting the desired balance between hydrophilic and hydrophobic elements.

Examples of the above condensation products are condensates of straight or branched chain aliphatic alcohols having 6 to 22 carbon atoms with ethylene oxide, such as the condensate of coconut oil with ethylene oxide, which contains 2 to 15 moles of ethylene oxide per mole of coconut alcohol; condensates of alkylphenols having 6 to 12 carbon atoms in the alkyl chain, which contain 5 to 25 moles of ethylene oxide per mole of alkylphenol; condensates of the reaction product of ethylenediamine and propylene oxide with ethylene oxide, which contain 40 to 80 wt. % of polyoxyethylene groups and have a molecular weight in the range of 5,000 to 11,000; tertiary amine oxides of the general formula R3NO, in which one R substituent is an alkyl group of 8-18 carbon atoms and the other R substituents are methyl, ethyl or hydroxyethyl groups - such as dimethyldodecylamine oxide; tertiary phosphine oxides of the general formula _R3PO ,

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PCT/EP97/07152 in which one R substituent is an alkyl group of 10-18 carbon atoms and the other R substituents are alkyl or hydroxyalkyl groups of 1-3 carbon atoms - such as dimethyldodecylphosphine oxide; and dialkyl sulfoxides of the general formula R ₂ SO in which one R substituent is an alkyl group of 10-18 carbon atoms and the other R substituent is methyl or ethyl - such as methyltetradecyl sulfoxide; fatty acid alkylolamides; and also condensates of fatty acid alkylolamides and alkyl mercaptans with alkylene oxide.

Particularly preferred nonionic surfactants are alcohols having 6-14 carbon atoms and ethoxylated with 2-9 moles of ethoxy groups. Suitable materials include the tradename IMBENTIN 91/35 OFA (a C9-11 nonionic surfactant containing an average of 5 moles of ethoxy groups) and the tradename NONIDET 91-6T (a C9-11 reduced nonionic surfactant containing an average of 6 moles of ethoxy groups).

Many other nonionic surfactants are known to those skilled in the art from the prior art [M. J. Schick: Nonionic Surfactants, Marcel Dekker, 1967],

The amount of nonionic surfactant used in the composition according to the invention is generally 1-30% by weight, preferably 2-20% by weight, most preferably 5-10% by weight.

The weight ratio of nonionic surfactant to anionic and cationic surfactants is preferably such that greater than 75% by weight of the total surfactants in the composition are nonionic surfactants.

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It is essential that the compositions of the invention contain only very small amounts of anionic surfactants, or that the compositions are free from anionic surfactants as far as is practical. The presence of anionic surfactant is believed to lead to complexation between cationic and anionic surfactants, which reduces the effectiveness of the compositions.

The total amount of surfactants in the compositions of the invention is generally 1-30% by weight.

Organic amines

It is essential that the compositions of the invention contain at least 0.5% by weight of an organic amine having _a pK a of at least 8.0. This component is believed to act as an ester cleavage agent, which aids in the removal of stubborn soils, such as pyrolyzed soils formed on the surface during heating of fatty and/or proteinaceous foods. When organic amines with low pK _a values, such as aniline, are used, they are ineffective in assisting cleaning. If a significant amount of inorganic base is present, the quaternary material described above flocculates and the composition separates into phases.

The composition preferably contains 1-10% by weight, more preferably 2-6% by weight of alkanolamine. Particularly preferred alkanolamines are 2-amino-2-methyl-1-propanol, monoethanolamine and diethanolamine. The most preferred organic amine is 2-amino-2-methyl-1-propanol.

The compositions of the invention preferably contain less than 1% by weight of salts (forming electrolytes) which

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- s - »·' ·«··..’.:..

they may include, among others, sodium and/or potassium carbonate, bicarbonate and/or hydroxide.

Small amounts and other ingredients

The compositions of the invention may contain a number of minor components. The compositions of the invention may also contain other components to improve the cleaning performance and/or physical properties of the composition. These components are not essential to the principle of the invention.

Hydrophobic oils are optional components of the compositions of the invention. Suitable oils include those oils which readily dissolve triglycerides. When oils are present in the composition, they are preferably limonene, paracymol, dibutyl ether and butyl butyrate.

A further optional ingredient of the compositions of the invention is a suds control agent, which is used in cases where the composition is prone to excessive foaming during use. Suds control agents may include, but are not limited to, solvent solvents, hydrophobic silica, and silicone oils or hydrocarbons.

Solvents are optional components of the compositions of the invention. If solvents are used, they are preferably solvents of the general formula R ₁ -O-(EO) _m -(PO) _n -R ₂ , in which R 1 and R ₂ are independently C 2-6 alkyl or hydrogen, with the proviso that at least one of the substituents is 89942-2227C/VO/LZS

PCT/EP97/07152 • ♦Ο φ.» » ♦·» I*· » » “ θ ‘•-^'Μ· lent is other than a hydrogen atom; η and m are independently a number from 0 to 5. The solvent is more preferably selected from diethylene glycol mono-n-butyl ether, monoethylene glycol mono-n-butyl ether, propylene glycol n-butyl ether, isopropanol, ethanol, butanol and mixtures thereof. Further possible solvents are pyrrolid(in)ones, such as N-methylpyrrolidinone.

It has been found that the use of a long chain fatty alcohol, preferably an alcohol of at least 16 carbon atoms, more preferably an alcohol of 16-20 carbon atoms, such as tallow alcohol, improves the cleaning performance. These alcohols are typically present in an amount of 0.001-2% by weight, preferably up to 1% by weight.

The compositions of the invention may contain, in addition to the ingredients already mentioned, other optional ingredients, which may include pH adjusting agents, colorants, optical brighteners, soil release agents, detergent enzymes, compatible bleaching agents, gelling agents, freeze/thaw stabilizers, bactericides, preservatives, detergent hydrotropes, fragrances and opacifiers.

It has been found convenient to deliver the product of the invention in a relatively fine spray for relatively small doses of product. This has the significant advantage that only a small amount of product is required. The compositions of the invention are preferably packaged in a container that delivers 0.1-1.5 ml of spray per actuation, where the average droplet size of the spray is in the range of 30-300 μη.

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It has been found that it is particularly advantageous to include a polymer in the compositions of the invention to reduce the formation of extremely fine droplets when the composition is applied as a relatively fine spray. An example of a suitable polymer is polyvinylpyrrolidone, which is commercially available under the trade name Polymer PVP K-90.

Poly(vinylpyrrolidone) is suitably used in an amount of at least 50 ppm, particularly preferably 300-2000 ppm.

Particularly preferred compositions have a pH greater than 10 and contain the following ingredients in a mixture with water:

a) 3-15% by weight of nonionic surfactant (preferably a nonionic surfactant having 9-12 carbon atoms and containing 5-8 EO units);

b) 2-10% by weight of solvent (preferably diethylene glycol mono-n-butyl ether);

c) 2-6% by weight of an alkanolamine (preferably 2-amino-2-methyl-1-propanol);

d) 0-2000 ppm polymer (preferably PVP) and

f) 0.1-4% by weight of a cationic surfactant comprising a cation of the general formula [RtR ₂ R ₃ R ₄ N] ⁺ X', in which R ₁₍ R ₂ and R ₃ independently represent an alkyl group having 1-6 carbon atoms, R ₄ represents an aliphatic alkyl group containing at least 10% by weight of an alkyl group having 18-26 carbon atoms, and X represents a monovalent anion.

The invention is illustrated in the following by non-limiting examples.

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As shown in Table 1, aqueous compositions containing nonionic surfactant and relatively small amounts of cationic surfactant are prepared using the materials listed below (unless otherwise indicated, the compositions given are in % by weight).

FEMALE: Trade name substance NONIDET 91-6T - ethoxylated alcohol with 9-11 carbon atoms, containing 6 moles of ethoxy groups, which is reduced to reduce the amount of low molecular weight ethoxylates (manufacturer: Nippon Shell),

VBM: benehyl trimethyl ammonium chloride (manufacturer: Nippon Oils and Fats),

Dl GOAL: Buti I-Di goi trade name substance - diethylene glycol mono-n-butyl ether,

AMP: 2-amino-2-methyl-1-propanol,

CTAB: cetyltrimethylammonium bromide (manufacturer: BDH),

DEA: diethanolamine,

CARB: potassium carbonate,

POL: PVP K-90 (manufacturer: International Speciality Polymers),

2HT: NISSAN CATION 2ABTN is a product with the trade name di(hardened)tallow dimethyl ammonium chloride (manufacturer: Nippon Oils and Fats).

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Table 1

component example (% by weight) 1. 2. 3. 4. 5. WOMEN 10 10 10 10 10 DIGOL 8 8 8 8 8 AMP 4 4 4 4 4 CARB - - - - 1.25 VBM 0 1 0 0 1 CTAB 0 0 0 1 0 2HT 0 0 1 0 0 Eth 1097 560 634 735 - stability + + - + -

All samples contain 0.1 wt% of polyvinylpyrrolidone, trade name Polymer PVP K-90, and 0.2 wt% of fragrance.

To prepare the composition according to Example 1, the desired amount of all the ingredients is mixed at room temperature. In Examples 2 and 5, the VBM component is added to hot water at 80 °C and mixed with a Heidolph mixer at 80 °C for 2 hours, thereby obtaining a solution with a concentration of 15.5% by weight. The desired amount of this solution (maintained at 80 °C) is added to the required amount of the solution containing all the other ingredients at room temperature, and the resulting mixture is mixed for a further 10 minutes. In Example 3, the nonionic surfactant (NŐNI) and di(hardened)tallow dimethyl ammonium chloride are used in the same proportions.

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PCT/EP97/07152 are melted together at 60°C. The desired amount of this co-melt (maintained at 60°C) is added to the required amount of the solution containing all the other ingredients at room temperature and the mixture is stirred for a further 30 minutes. In the case of Example 4, the required amount of all the ingredients is stirred together at room temperature. The solution is then heated briefly to 60°C for homogenization.

The following experiments are carried out to determine the results of the cleaning. 100 g of anhydrous castor oil with a viscosity of 0.15 Pa (manufacturer: SEATONS) are weighed into a glass jar. 0.2 g of the dye Fát Red (manufacturer: SIGMA) is added to the castor oil and the mixture is stirred intensively (2000 rpm) for 6 hours with a Heidolph type mixer. The mixed mixture is stored in a refrigerator when not in use. Enameled tiles (380 x 300 mm in size) are cleaned using a new moistened J-cloth, JIF paste, then a commercially available liquid hand dishwashing detergent and finally calcite powder. After drying, the remaining calcite is removed with a paper towel.

Rub 1 ml of each of the formulations listed in Table 1 onto the cleaned tiles using a clean, moistened J-wipe. Rinse the tiles under running water for 15 seconds to remove excess product, then allow the rinse water to drain. Spray the tiles over an area measuring 215 x 150 mm using a DeVilbiss MPS-514/515 gravity feed spray gun.

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PCT/EP97/07152 is used with compressed air at a pressure of 172.2 kPa, the atomization is continued for a period of 35 s from a distance of 27 cm. The soiled tiles are placed in a horizontal position in an oven at a temperature of 85 °C, thermally aged for 1.5 hours, and then stored overnight.

The tiles are cleaned by hand using a damp J-wipe and the products listed in Table 1. The force required to clean the tiles is given in the ETh row of Table 1 in Ns units, where higher values indicate that more force is required to clean the tiles.

To determine stability, samples were stored at 5 °C, 25 °C and 37 °C for 3 months. Products marked as unstable in Table 1 showed the formation of an opalescent precipitate under at least one of the above storage conditions.

It can be seen from the data in Table 1 that the lowest cleaning effort is experienced in the case of the composition according to Example 2, which is a composition according to the invention in which a quaternary cationic VBM component containing a longer aliphatic chain alkyl group is present. The compositions according to Examples 3 and 4 also show an improvement compared to the control composition according to Example 1. It can be seen that either the degree of improvement is small, as in the case of the component containing a shorter aliphatic alkyl chain (see the CTAB component used in Example 4) or the storage stability of the product is lost, as in the case of the di(a) alkyl compound (see the 2HT component used in Example 3).

PCT/EP97/07152

- ¹⁵ - ·..::.. · .· · .· ·· ·· ·« ·«······ part). Example 5 illustrates that combining an alkali metal salt and a VBM component does not result in a stable product.

Further test results are presented in Table 2. The raw materials used are as above, and the interpretation of ETh is also as above. The sample according to Example 11 is prepared according to Example 1, the samples according to Examples 6, 7, 9 and 10 are prepared according to Examples 2 and 5, while the sample according to Example 8 is prepared according to Example 3.

Table 2 shows the percentage values obtained for the removal of soiling using a WIRA (Wool Industries Research Association) abrasive. In these tests, 10 x 10 cm stainless steel plate samples are cleaned with calcite and then rinsed with deionized water. 25 g of salad oil (manufacturer: Nisshin, JP), 5 g of household flour (Homepride brand product, manufacturer: Dalgety, GB) and 75 g of acetone are mixed for 2 minutes using a high shear Si Iverson type mixer. The resulting mixture is then sprayed onto the cleaned plate samples using a Humbrol type paint spray gun, using a circular mask, thus obtaining a 5.5 cm diameter soiling spot. After evaporation of the acetone, 0.04-0.05 g of soiling remains. The soiled plate samples are heated to 175 °C for 34 minutes and then stored overnight until cleaning. The soiled plate sample is placed in the WIRA abrasion device and 0.5 ml of the test product is applied to it. The plate sample is then cleaned with an eight-fold J-wipe (manufacturer: Johnson and Johnson, UK) for one complete cycle (17 strokes of the head), the load weight applied to the cleaning head being 657 g/cm ² . This procedure is repeated 89942-2227C/VO/LZS

PCT/EP97/07152 is run through three complete cycles, each cycle using a fresh J-wipe and 0.5 ml of the test product. After each of the three cycles, the contaminated plate sample is removed from the apparatus, rinsed and then allowed to dry at 50°C for 30 minutes. The total mass of contamination removed is calculated and expressed as a % of the original mass of the original contamination. These results are reported in Table 2 as WIRA.

CB is the contact angle of the composition of the examples with glass, where bromonaphthalene is used in the test.

Table 2

component (% by weight) example 6. 7. 8, 9. 10. 11. WOMEN 10 10 10 10 10 10 DIGOL 8 8 8 8 8 8 AMP 4 - 4 - 4 4 DEA - 4 - - - - CARB - - - - 1.25. 1.25 VBM. 1 1 0 1 1 0 CTAB 0 0 1 0 0 0 Eth 185 474 1383 336 742 2919 WIRA 88 84 83 57 85 89 CB 27 31.8 23.6 29 30 20.1

Examples 6, 7 and 10 relate to a composition according to the invention, while the remaining examples are comparative examples. Example 11 relates to a commercial kitchen cleaner.

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PCT/EP97/07152 ¹⁷ ·.:·:: ^: .::.

Table 2 shows that higher cleaning power (ETh) is required when the formulation does not contain a quaternary cationic surfactant (Example 11) or when the alkyl chain in the quaternary cationic surfactant is short (Example 8).

The results obtained with the WIRA abrasion device - where higher scores indicate better results - show that the presence of organic amines AMP (Examples 6 and 10) or DEA (Example 7) significantly increases the effectiveness of the composition compared to an amine-free composition (Example 9).

CB data demonstrate that the compositions of the invention modify the surface energy (calculated from the contact angle) compared to a known kitchen cleaner (Example 11) that does not contain a quaternary cationic surfactant. The surface energy modification is less for CTAB-based formulations (Example 8).

From the comparison of the data, it can be seen that the compositions of Examples 6 and 7 require less cleaning effort and modify the surface energy to prevent or reduce resoiling of the surface. The composition of Example 8 is less effective, especially for thermally aged soils. The composition of Example 9 attacks the thermally aged soil used for ETh determination, but is less effective as a general cleaning agent. The composition of Example 10 is acceptable, but carbonate-free compositions are preferred.

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Claims (10)

Patent claims 1. Aqueous cleaning agents for solid surfaces containing a mixture of surfactants, where the mixture of surfactants is based on the total amount of surfactants a) at least 65% by weight of non-ionic surfactants, b) less than 1% by weight of anionic surfactants and c) 0.1-35% by weight of a cationic surfactant which is a monoaliphatic quaternary alkyl ammonium compound, wherein the chain a I ki I contains at least 10% by weight of alkyl groups having 18-26 carbon atoms, wherein the cleaning agent further comprises at least 0.5% by weight of an organic amine having a pK _a value of at least 8.0. 2. Cleaning agents according to claim 1, wherein the monoaliphatic quaternary alkyl ammonium compound is a compound of the general formula (I), [R ₁ R ₂ R ₃ R ₄ N] ⁺ X· (I) in which R^ R ₂ and R ₃ are independently an alkyl group having 1-6 carbon atoms, R ₄ is an aliphatic alkyl group, and X is a monovalent anion, and the distribution of the carbon chain lengths is such that less than 60% by weight of the monoaliphatic quaternary alkyl ammonium compound contains an aliphatic alkyl chain having up to 16 carbon atoms. 3. Cleaning agents according to claim 2, wherein R _1, R ₂ and R ₃ are methyl. 89942-2227C/VO/LZs PCT/EP97/07152 - ¹⁹ - _# ζ ·,,· · .· 4. Cleaning agents according to any one of claims 1-3, which contain trimethylbehenyl ammonium halide as monoaliphatic quaternary alkyl ammonium compound. 5. Cleaning compositions according to claim 1, which contain a nonionic surfactant in a weight ratio relative to the anionic and cationic surfactants, where the nonionic surfactant is present in an amount greater than 75% by weight, based on the total amount of surfactants present in the cleaning composition. 6. Cleaning agents according to claim 1, which contain 2-10% by weight of organic amine. 7. Cleaning agents according to claim 1, which contain an organic amine selected from 2-amino-2-methyl-1-propanol, monoethanolamine and diethanolamine. 8. Cleaning agents according to claim 1, packaged in a container suitable for producing a spray of 0.1-1.5 ml per spray operation, wherein the average droplet size of the spray is in the range of 30-300 μη. 9. Cleaning agents according to claim 1, having a pH greater than 10, which, in a mixture with water, contain a) 3-15% by weight of nonionic surfactant, b) 2-10% by weight of solvent, c) 2-6% by weight of organic amine, d) 0-2000 ppm of polymer and e) 0.1-4% by weight of a cationic surfactant of general formula (I) [R ₁ R ₂ R ₃ R ₄ N] ⁺ X (I) - in which R1, _R2 and _R3 are independently 1-6 89942-2227C/VO/LZS PCT/EP97/07152 C alkyl group, R ₄ is at least 10% by weight of an aliphatic alkyl group having 18-26 carbon atoms, and X is a monovalent anion. 10. A method for cleaning solid surfaces, characterized in that the surface is treated with a cleaning agent according to any one of claims 1-9, wherein the cleaning agent is sprayed onto the surface. On behalf of UNILEVER NV, the authorized representative: DANUBE Patent and Trademark Office Ltd. Dr. László Vitalis, patent attorney 89942-2227C/VO/LZS PCT/EP97/07152