Acidic cleaning compositions

Abstract

 The present invention is a liquid acidic composition comprising from 0.01% to 45% by weight of the total composition of maleic acid, from 0.01% to 25% by weight of a second acid having its first pKa not exceeding 5, and an amine according to the formula RR'R''N, wherein R is a saturated or unsaturated, substituted or unsubstituted, linear or branched alkyl group of from 1 to 30 carbon atoms, and wherein R' and R'' are independently saturated or unsaturated, substituted or unsubstituted, linear or branched alkyl groups of from 1 to 30 carbon atoms or hydrogen. These compositions deliver excellent limescale removal performance as well as outstanding greasy soap scum cleaning on hard-surfaces.

Description

Technical field

[0001] The present invention relates to cleaning compositions for hard-surfaces. More specifically, the compositions of the present invention give optimal performance in removing limescale-containing stains typically found in a kitchen or in a bathroom.

Background

[0002] Tap water contains a certain amount of solubilized ions which upon water evaporation eventually deposit as salts such as calcium carbonate on surfaces which are often in contact with said water, resulting in an unaesthetic aspect of said surfaces. This limescale formation and deposition phenomenon is even more acute in places where water is particularly hard.

[0003] It is well-known in the art that limescale deposits can be chemically removed with acidic solutions, and a great variety of acidic cleaning compositions have been described for this purpose.

[0004] However, the state of the art liquid acidic limescale removal compositions do not perform equally well on all limescale-containing stains, particularly on limescale-containing stains which can be found in bathrooms or in kitchens, i.e., on stains containing mineral deposits like calcium carbonate but also high amount of organic deposits such as greasy soap scum. Indeed, the presence of such greasy soap scum is detrimental to the limescale removal performance of acidic compositions.

[0005] To overcome this problem liquid acidic limescale removal compositions have been formulated that comprise on top of the acid, a surfactant to deliver effective cleaning on organic soils. Representative of the art is for example, EP-A-496 188 which discloses liquid acidic compositions comprising maleic acid and nonionic surfactants for the cleaning of limescale-containing bathroom-type stains.

[0006] However, it has now been observed that surfactants like nonionic surfactants have a negative impact on limescale removal properties of acids, and thus decrease the limescale removal performance of an acidic composition comprising them. Also such compositions based on acids and nonionic surfactants are not fully satisfactory from a consumer point of view in terms of greasy soap scum cleaning.

[0007] Thus, there is a constant strive for the development of limescale removal compositions with better performance in several respects including outstanding greasy soap scum cleaning performance and excellent limescale removal performance.

[0008] It is therefore an object of the present invention to provide a liquid composition for the removal of limescale-containing stains which can be found in a kitchen or in a bathroom, said composition delivering improved greasy soap scum cleaning and improved limescale removal performance.

[0009] It has now been found that the above object is met by formulating an acidic composition comprising an acidic system, i.e., maleic acid and a second acid having its first pKa not exceeding 5, and a particular surfactant, i.e., an amine according to the formula RR'R''N, wherein R is a saturated or unsaturated, substituted or unsubstituted, linear or branched alkyl group of from 1 to 30 carbon atoms, and wherein R' and R'' are independently saturated or unsaturated, substituted or unsubstituted, linear or branched alkyl groups of from 1 to 30 carbon atoms or hydrogen. In other words, the compositions of the present invention allow to deliver at the same time optimum limescale removal performance by combining maleic acid with said second acid and adding thereto a surfactant (i.e., amine) with a minimal impact on the limescale removal properties of said acidic system, and optimum greasy soap scum cleaning performance due to said amine.

[0010] In a broader aspect of the present invention, it has been found that the use of an amine, as described herein, in an acidic liquid composition, allows to improve the greasy soap scum cleaning performance as well as the limescale removal performance of said composition, as compared to the use of another surfactant like a nonionic surfactant (e.g., Dobanol® 91-8), instead of said amine, this even at a lower total surfactant level. In one embodiment the present invention also encompasses a process for removing limescale-containing stains, for example bathroom-type or kitchen-type limescale-containing stains, from a hard-surface, wherein a liquid acidic composition comprising an amine, as described herein, is applied in its neat form or in diluted form, onto said surfaces, then left to act onto said surface and then removed by rinsing.

[0011] An advantage of the present invention is that the compositions of the present invention deliver improved greasy soap scum cleaning performance and excellent limescale removal performance while being safe to the surface treated. Indeed, the compositions of the present invention comprising maleic acid on top of said second acid having a first pka not exceeding 5 are significantly safer to the surfaces treated therewith, as compared to the same compositions without maleic acid whilst maintaining the advantage in limescale removal performance of said second acid having its first pKa not exceeding 5. Thus, the compositions herein are particularly suitable for applications on a variety of surfaces including synthetic materials, ceramic as well as any type of metal (e.g. aluminium, stainless steel, chromed steel and the like).

[0012] EP-A-601 990 discloses an acidic composition comprising an acid for example maleic acid together with a thickening system comprising from 0.5% to 15% by weight of the total composition of a mixture of a nonionic surfactant and a cationic surfactant. No primary, secondary or tertiary amines are disclosed.

[0013] WO 95/07335 discloses mildly acidic (pH=3 to 7) no-rinse hard surfaces liquid compositions. The compositions contain from 1% to 50% by weight of an amine oxide and an acidifying agent having a pKa of less than 6. No primary, secondary or tertiary amines are disclosed.

[0014] GB 1 240 469 discloses a hard-surface cleaning composition which has a pH of not more than 7 and comprises (a) an inorganic or organic acid, or an acidic salt (5% to 95%), (b) a cationic surfactant (0.01% to 10%), and (c) a covalent compound other than (b) and which contains oxygen or a halogen and at least one hydrocarbon chain having at least four carbon atoms. No primary, secondary or tertiary amines are disclosed.

[0015] EP-A-130 786 discloses an acidic composition (pH=1 to 5) comprising a weak organic and a weak inorganic acid (5% to 25%), a surfactant system comprising a major proportion of an amine oxide (2% to 15%) and a cosolvent, said composition being preferably applied to the soils as a foam. No primary, secondary or tertiary amines are disclosed.

[0016] GB 2 106 927 discloses liquid thickened toilet bowl cleaners comprising a non volatile water soluble organic acid, a surfactant, and a cellulose ether, said composition having a pH of 2.2 to 3.5. No primary, secondary or tertiary amines are disclosed.

[0017] EP-A-666 305 discloses a liquid acidic composition comprising maleic acid and a second acid having its first pKa not exceeding 5 and surfactants. No primary, secondary or tertiary amines are disclosed.

[0018] EP-A-253 676 discloses a thickened aqueous composition comprising at least one acidic salt, e.g., maleic acid (0.01%-30%), and a thickening agent (0.1% to 10%) which is at least one of the compounds selected from the group consisting of amine or amine oxide surfactants. No acidic system according to the present invention, i.e., maleic acid (0.01%-45%) and a second acid having its first pKa not exceeding 5 (0.01%-25%) is disclosed, nor exemplified. EP-A-253 676 does not refer to the removal of limescale-containing stains like those found in bathrooms or kitchens.

Summary of the invention

[0019] The present invention is a liquid acidic composition comprising from 0.01% to 45% by weight of the total composition of maleic acid, from 0.01% to 25% by weight of a second acid having its first pKa not exceeding 5, and an amine according to the formula RR'R''N, wherein R is a saturated or unsaturated, substituted or unsubstituted, linear or branched alkyl group of from 1 to 30 carbon atoms, and wherein R' and R'' are independently saturated or unsaturated, substituted or unsubstituted, linear or branched alkyl groups of from 1 to 30 carbon atoms, or hydrogen.

[0020] The present invention also encompasses a process of treating hard-surfaces soiled by limescale-containing stains, wherein an acidic liquid composition according to the present invention is applied in its neat form or in diluted form, onto said surfaces, then left to act onto said surfaces and then removed by rinsing.

[0021] In a broader aspect, the present invention encompasses a process of treating hard-surfaces soiled by limescale-containing stains, preferably bathroom-type and/or kitchen-type limescale-containing stains, wherein an acidic liquid composition comprising an amine, as described herein, is applied in its neat form or in diluted form, onto said surfaces, then left to act onto said surfaces and then removed by rinsing.

[0022] The present invention further encompasses the use, of an amine according to the formula RR'R''N, wherein R is a saturated or unsaturated, substituted or unsubstituted, linear or branched alkyl group of from 1 to 30 carbon atoms, and wherein R' and R'' are independently saturated or unsaturated, substituted or unsubstituted, linear or branched alkyl groups of from 1 to 30 carbon atoms, or hydrogen, in an acidic limescale removal composition, to improve the greasy soap scum cleaning performance of said composition.

Detailed description of the invention

[0023] The compositions according to the present invention are designed for removing limescale deposits. Thus, they comprise maleic acid as an essential ingredient. Accordingly, the compositions according to the present invention comprise from 0.01% to 45% by weight of the total composition of maleic acid, preferably from 1% to 25% and more preferably from 8% to 20%. This percentage is calculated on the basis of the molecular weight of the acid form, but maleic anhydride is equally convenient for use in the compositions according to the present invention. Indeed, maleic anhydride is generally cheaper and it is transformed into the acid form when incorporated in an aqueous medium.

[0024] The compositions according to the present invention comprise a second acid which has a first pKa not exceeding 5, as a further essential ingredient. Said second acid is desired to strengthen the limescale removal performance. Preferably the second acids to be used herein which are particularly efficient to remove limescale on many surfaces, have their first pKa not exceeding 4, more preferably not exceeding 3, and most preferably not exceeding 2. According to the present invention said acids can be organic or inorganic acids. Examples of inorganic acids are sulphonic acid derivatives, sulphamic acid (pKa=0.1), hydrochloric acid (pKa<0), nitric acid (pKa<0), phosphoric acid (pKa=2.1) and sulphuric acid (pKa=0.4). An example of organic acid is citric acid (pKa=3.06). Particularly suitable to be used herein are sulphonic acid derivatives including alkyl sulphonic acids and aryl sulphonic acids.

[0025] Suitable alkyl sulphonic acids for use herein are C1-C6 linear or branched alkylsulphonic acids or mixtures thereof, such as methanesulphonic acid (pKa=1.9) commercially available for example from Aldrich, William Blythe & Co. Ltd. or Elf. Atochem.

[0026] Suitable aryl sulphonic acids for use herein are according to the formula :

wherein R₁, R₂, R₃, R₄ and R₅ are each H or SO₃H, or linear or branched C₁-C₄ alkyl chain; or mixtures thereof.

[0027] Preferred arylsulphonic acids to be used according to the present invention are those which comprise no or only one alkyl chain. Indeed, we have found that said arylsulphonic acids are particularly effective at removing limescale, which is not the case for their longer alkyl chain homologues. Also, we have found that said arylsulphonic acids are particularly safe to the surface treated therewith. Particularly suitable arylsulphonic acids for use herein are benzene sulphonic acid (pKa=0.7), toluene sulphonic acid and cumene sulphonic acid. Amongst these three, at equal weight %, we have found that the shorter the alkyl chain, down to no chain at all, the better the limescale removing performance.

[0028] Preferred acids having a first pKa not exceeding 5 to be used herein are sulphamic acid, sulphuric acid, aryl sulphonic acids, alkyl sulphonic acids, or mixtures thereof, more preferred are sulphamic acid, sulphuric acid, benzene sulphonic acid or mixtures thereof and most preferred is sulphamic acid.

[0029] The compositions of the present invention comprise from 0.01% to 25% by weight of the total composition of a second acid which has a first pKa not exceeding 5, or mixtures thereof, preferably from 0.1% to 20%, more preferably from 0.1 % to 10%, and most preferably from 0.1% to 7%.

[0030] The compositions according to the present invention comprise as a further essential ingredient an amine, as described herein after, or mixtures thereof.

[0031] Suitable amines to be used herein are according to the following formula RR'R''N wherein R is a saturated or unsaturated, substituted or unsubstituted, linear or branched alkyl groups of from 1 to 30 carbon atoms, and preferably of from 1 to 20 carbon atoms and wherein R' and R'' are independently saturated or unsaturated, substituted or unsubstituted, linear or branched alkyl groups of from 1 to 30 carbon atoms or hydrogen. Particularly preferred amines to be used according to the present invention are amines having the following formula RR'R''N wherein R is a saturated or unsaturated, linear or branched alkyl group of 1 to 30 carbon atoms, preferably of 8 to 20 carbon atoms, more preferably of 6 to 16, most preferably of 8 to 14 and wherein R' and R'' are independently substituted or unsubstituted, linear or branched alkyl groups of from 1 to 4 carbon atoms, preferably of from 1 to 3 carbon atoms, and more preferably are methyl groups, or mixtures thereof.

[0032] Suitable amines for use herein are for instance C12 dimethyl amine, coconut dimethyl amine, C12-C16 dimethyl amine. Said amines may be commercially available from Hoechst under the trade name Genamin®, AKZO under the trade name Aromox® or Fina under the trade name Radiamox®.

[0033] The compositions of the present invention comprises from 0.01% to 20% by weight of the total composition of said amine, or mixtures thereof, preferably from 0.1% to 10%, more preferably from 0.1% to 5%, and most preferably from 0.4% to 3%.

[0034] The presence of amines according to the present invention allows to lower the surface tension and to improve the wettability of the surfaces being cleaned with the liquid acidic compositions of the present invention. The presence of said surfactant in the liquid acidic compositions of the present invention helps to solubilize the soils and to improve the streaking profile of the acids.

[0035] It has now been found that the compositions of the present invention comprising maleic acid, said second acid and an amine, as described herein, provide improved greasy soap scum cleaning performance as well as improved limescale removal performance, as compared to the greasy soap scum cleaning performance and limescale removal performance obtained with the same composition but with another surfactant like a nonionic surfactant, e.g. an alcohol ethoxylate (Dobanol® 91-8), instead of said amine, this even at significantly lower total surfactant level. Indeed, it has now been found that the impact of amines on the limescale removal properties of acids is minimal as compared to other surfactants like nonionic surfactants.

[0036] In a broader aspect of the present invention, it has been found that the addition of an amine, as defined herein, in a liquid acidic composition provides improved greasy soap scum cleaning performance, as compared to the same composition without any surfactant or to the same composition but with another surfactant, this while providing excellent limescale removal performance. Thus, the present invention also encompasses the use, in an acidic liquid limescale removal composition, of an amine, as defined herein, to improve the greasy soap scum cleaning performance of said composition.

[0037] The liquid compositions according to the present invention are preferably aqueous. Accordingly, the compositions according to the present invention comprise from 10% to 95% by weight of the total composition of water, preferably from 50% to 90%, most preferably from 70% to 85%.

[0038] The compositions according to the present invention are liquid acidic compositions. The compositions according to the present invention have a pH as is below 3, preferably in the range of from 0.1 to 2.5, more preferably of from 0.1 to 2, and most preferably of from 0.3 to 1.5.

[0039] Also the acidic liquid compositions of the present invention are physically stable, i.e. that no phase separation occurs when stored in rapid aging test (RAT) at 50 °C for 10 days or at 2 °C for 2 months.

[0040] The compositions according to the present invention may further comprise a variety of other ingredients including other surfactants, colorants, bactericides, thickeners, dyes, chelants, pigments, solvents, stabilizers, perfumes, corrosion inhibitors and the like.

[0041] Accordingly, the compositions according to the present invention may further comprise other surfactants or mixtures thereof. The compositions according to the present invention may comprise up to 30% by weight of the total composition of said other surfactant or mixtures thereof on top of amines of the present invention, more preferably from 0.05% to 10%, more preferably from 0.1% to 8%, and most preferably from 0.1% to 3%. All types of surfactants may be used in the present invention including nonionic, anionic, cationic, amphoteric or zwitterionic surfactants. It is also possible to use mixtures of such surfactants without departing from the spirit of the present invention.

[0042] Suitable nonionic surfactants to be used herein are alkoxylated alcohol nonionic surfactants which can be readily made by condensation processes which are well-known in the art. However, a great variety of such alkoxylated alcohols, especially ethoxylated and/or propoxylated alcohols is also conveniently commercially available. Surfactants catalogs are available which list a number of surfactants, including nonionics.

[0043] Accordingly, preferred alkoxylated alcohols for use herein are nonionic surfactants according to the formula RO(E)e(P)pH where R is a hydrocarbon chain of from 2 to 24 carbon atoms, E is ethylene oxide and P is propylene oxide, and e and p which represent the average degree of, respectively ethoxylation and propoxylation, are of from 0 to 24. The hydrophobic moiety of the nonionic compound can be a primary or secondary, straight or branched alcohol having from 8 to 24 carbon atoms. Preferred nonionic surfactants for use in the compositions according to the invention are the condensation products of ethylene oxide with alcohols having a straight alkyl chain, having from 6 to 22 carbon atoms, wherein the degree of ethoxylation is from 1 to 15, preferably from 5 to 12. Such suitable nonionic surfactants are commercially available from Shell, for instance, under the trade name Dobanol^R or from Shell under the trade name Lutensol^R. These nonionics are preferred because they have been found to allow the formulation of a stable product without requiring the addition of stabilisers or hydrotopes. When using other nonionics, it may be necessary to add hydrotopes such as cumene sulphonate or solvents such as butyldiglycolether.

[0044] Suitable anionic surfactants for use herein are according to the formula R₁SO₃M wherein R₁ represents a hydrocarbon group selected from the group consisting of straight or branched alkyl radicals containing from 6 to 24 carbon atoms and alkyl phenyl radicals containing from 6 to 15 carbon atoms in the alkyl group. M is a salt forming cation which typically is selected from the group consisting of sodium, potassium, ammonium, and mixtures thereof.

[0045] Other suitable anionic surfactants can be represented by the water-soluble salts of an alkyl sulfate or an alkyl polyethoxylate ether sulfate wherein the alkyl group contains from 6 to 24 carbon atoms, and preferably from 1 to 30 ethoxy groups for the alkyl polyethoxylate ether sulfates.

[0046] Suitable cationic surfactants to be used herein include derivatives of quaternary ammonium, phosphonium, imidazolium and sulfonium compounds. Preferred cationic surfactants for use herein are according to the formula R₁R₂R₃R₄N⁺ X^-, wherein X is a counteranion, R₁ is a C₈-C₂₀ hydrocarbon chain and R₂, R₃ and R₄ are independently selected from H or C₁-C₄ hydrocarbon chains. In a preferred embodiment of the present invention, R₁ is a C₁₀-C₁₈ hydrocarbon chain, most preferably C₁₂, C_14,, or C₁₆, and R₂, R₃ and R₄ are all three methyl, and X is halogen, preferably bromide or chloride, most preferably bromide. Examples of cationic surfactants are lauryl trimethyl ammonium bromide, stearyl trimethyl ammonium bromide (STAB), cetyl trimethyl ammonium bromide (CTAB) and myristyl trimethyl ammonium bromide (MTAB). Highly preferred herein are lauryl trimethyl ammonium salts.

[0047] Indeed, it has been found that the addition of a cationic surfactant according to the formula R₁R₂R₃R₄N⁺ X^-, wherein X is a counteranion, R₁ is a C₈-C₁₂ hydrocarbon chain and R₂, R₃ and R₄ are independently selected from H or C₁-C₄ hydrocarbon chains, and preferably of lauryl trimethyl ammonium salts, in a liquid acidic composition, allows to improve the limescale removal performance of said composition. Thus, another aspect of the present invention is the use of a cationic surfactant according to the formula R₁R₂R₃R₄N⁺ X^-, wherein X is a counteranion, R₁ is a C₈-C₁₂ hydrocarbon chain and R₂, R₃ and R₄ are independently selected from H or C₁-C₄ hydrocarbon chains, preferably of lauryl trimethyl ammonium salts, in a liquid acidic composition, to improve the limescale removal performance of said composition.

[0048] Suitable zwitterionic surfactants contain both cationic and anionic hydrophilic groups on the same molecule at a relatively wide range of pH's. The typical cationic group is a quaternary ammonium group, although other positively charged groups like phosphonium, imidazolium and sulfonium groups can be used. The typical anionic hydrophilic groups are carboxylates and sulfonates, although other groups like sulfates, phosphonates, and the like can be used. A generic formula for some preferred zwitterionic surfactants is

        R₁-N⁺(R₂)(R₃)R₄X^-

wherein R₁ is a hydrophobic group; R₂ and R₃ are each C₁-C₄ alkyl, hydroxy alkyl or other substituted alkyl group which can also be joined to form ring structures with the N; R₄ is a moiety joining the cationic nitrogen atom to the hydrophilic group and is typically an alkylene, hydroxy alkylene, or polyalkoxy group containing from 1 to 4 carbon atoms; and X is the hydrophilic group which is preferably a carboxylate or sulfonate group. Preferred hydrophobic groups R₁ are alkyl groups containing from 8 to 22, preferably less than 18, more preferably less than 16 carbon atoms. The hydrophobic group can contain unsaturation and/or substituents and/or linking groups such as aryl groups, amido groups, ester groups and the like. In general, the simple alkyl groups are preferred for cost and stability reasons.

[0049] Other specific zwitterionic surfactants have the generic formulas:

        R₁-C(O)-N(R₂)-(C(R₃)₂)_n-N(R₂)₂⁽⁺⁾-(C(R₃)₂)_n-SO₃^(-) or R₁-C(O)-N(R₂)-(C(R₃)₂)_n-N(R₂)₂⁽⁺⁾-(C(R₃)₂)_n-COO^(-)

wherein each R₁ is a hydrocarbon, e.g. an alkyl group containing from 8 up to 20, preferably up to 18, more preferably up to 16 carbon atoms, each R₂ is either a hydrogen (when attached to the amido nitrogen), short chain alkyl or substituted alkyl containing from one to 4 carbon atoms, preferably groups selected from the group consisting of methyl, ethyl, propyl, hydroxy substituted ethyl or propyl and mixtures thereof, preferably methyl, each R₃ is selected from the group consisting of hydrogen and hydroxy groups and each n is a number from 1 to 4, preferably from 2 to 3, more preferably 3, with no more than one hydroxy group in any (C(R₃)₂) moiety. The R₁ groups can be branched and/or unsaturated. The R₂ groups can also be connected to form ring structures. A surfactant of this type is a C₁₀-C₁₄ fatty acylamidopropylene(hydroxypropylene)sulfobetaine that is available from the Sherex Company under the trade name "Varion CAS sulfobetaine"®.

[0050] Suitable amphoteric surfactants are surfactants which are similar to the zwitterionic surfactants but without the quaternary group. However, they contain an amine group that is protonated at the low pH of the composition to form cationic group and they may also possess an anionic group at these pHs.

[0051] Suitable amphoteric surfactants also include amine oxides. Suitable amine oxides to be used herein are according to the following formula R₁R₂R₃NO wherein each of R1, R2 and R3 is independently a saturated or unsaturated, substituted or unsubstituted, linear or branched alkyl groups of from 1 to 30 carbon atoms, and preferably of from 1 to 20 carbon atoms. Particularly preferred amine oxides to be used according to the present invention are amine oxides having the following formula R₁R₂R₃NO wherein R1 is a saturated or unsaturated, linear or branched alkyl group of 1 to 30 carbon atoms, preferably of 8 to 20 carbon atoms, more preferably of 6 to 16, most preferably of 8 to 14 and wherein R2 and R3 are independently substituted or unsubstituted, linear or branched alkyl groups of from 1 to 4 carbon atoms, preferably of from 1 to 3 carbon atoms, and more preferably are methyl groups, or mixtures thereof. Suitable amine oxides for use herein are for instance coconut dimethyl amine oxides, C12-C16 dimethyl amine oxides. Said amine oxides may be commercially available from Hoechst, Stephan, AKZO (under the trade name Aromox®) or FINA (under the trade name Radiamox®). Said amine oxides are preferred optional surfactants to be added on top of said amines as they further contribute to the benefit of the present invention. Indeed, they allow to further increase the greasy soap scum cleaning performance of the compositions of the present invention while further improving the limescale properties of said compositions. Thus, in an embodiment of the present invention, the preferred compositions herein further comprise said amine oxides.

[0052] The compositions according to the present invention are particularly suitable for treating hard-surfaces soiled by limescale-containing stains. By "limescale-containing stains" it is meant herein any pure limescale stains, i.e., any stains composed essentially of mineral deposits as well as any limescale-containing stains typically found, for example, in a kitchen or in a bathroom, i.e., stains which contain not only mineral deposits like calcium and/or magnesium carbonate but also soap scum (e.g., calcium stearate) and grease. Actually, the compositions of the present invention exhibit excellent limescale removing performance when used to treat any types of surfaces soiled by limescale-containing stains comprising not only pure limescale deposits but also at least 10% by weight of the total stain of organic deposits like soap scum and grease, preferably more than 30%. Such surfaces can be found in bathrooms, kitchens, but also in appliances including large appliances such as automatic dish washers and/or washing machines.

[0053] Accordingly, the present invention encompasses a process of treating hard-surfaces soiled by limescale-containing stains wherein an aqueous acidic liquid composition according to the present invention is applied in its neat form or in diluted form, onto said surfaces, then left to act onto said surfaces and then removed by rinsing. In another embodiment, the present invention also encompasses a process of treating hard-surfaces soiled by limescale-containing stains, preferably limescale-containing stains comprising mineral deposits and at least 10% by weight of the total stain of organic deposits like bathroom-type and/or kitchen-type limescale-containing stains, wherein an acidic liquid composition comprising an amine, as described herein, is applied in its neat form or in diluted form, onto said surfaces, then left to act onto said surfaces and then removed by rinsing.

[0054] The expression "used in diluted form" herein includes dilution by the user. Typical dilution levels are of from 0.5% to 50% by weight of the composition.

[0055] The expression "treating" includes removing limescale deposits while being safe to the surfaces treated as well as cleaning greasy soap scum stains due to the presence of said amine.

Examples

[0056] The present invention is further illustrated by the following examples. These compositions were made comprising the listed ingredients in the listed proportions (weight %).

Ingredients: (% by weight)	Compositions
	I	II	III	IV	V	VI
Maleic acid	10	7	2	10	8	6
Sulphamic acid	2	1	4	--	--	--
Citric acid	--	--	--	3	--	6
Benzensulphonic acid	--	--	--	--	2	--
C12 dimethyl amine	1	--	0.5	--	--	--
Coconut dimethyl amine	--	--	--	0.8	--	1
C12-C16 dimethyl amine	--	0.5	--	--	2	--
Coconut dimethyl amine oxide	--	--	--	0.5	--	--
C12-C16 dimethyl amine oxide	--	--	0.4	--	--	--
C8 dimethyl amine	--	0.5	--	--	--	1
Waters & Minors	----------------------up to 100 --------------------

[0057] All the compositions of the above examples exhibit excellent limescale removal performance as well as outstanding greasy soap scum cleaning performance when used to clean limescale-containing stains found in a kitchen and in a bathroom, this both when used neat or in diluted form. These compositions are also safe to the surfaces treated.

Claims

1. A liquid acidic composition comprising from 0.01% to 45% by weight of the total composition of maleic acid, from 0.01% to 25% by weight of a second acid having its first pKa not exceeding 5, and an amine according to the formula RR'R''N, wherein R is a saturated or unsaturated, substituted or unsubstituted, linear or branched alkyl group of from 1 to 30 carbon atoms, and wherein R' and R'' are independently saturated or unsaturated, substituted or unsubstituted, linear or branched alkyl groups of from 1 to 30 carbon atoms or hydrogen.

2. A composition according to claim 1 wherein second acid has its first pKa not exceeding 4, preferably not exceeding 3, and more preferably not exceeding 2.

3. A composition according to any of the preceding claims wherein said second acid is sulphamic acid, alkylsulfonic acid, arylsulfonic acid, citric acid, nitric acid, sulphuric acid, phosphoric acid, hydrochloric acid or mixtures thereof.

4. A composition according to any of the preceding claims wherein said composition comprises from 0.1% to 20% by weight of the total composition of said second acid, and preferably from 0.1% to 10%.

5. A composition according to any of the preceding claims wherein said composition comprises from 1% to 25% by weight of the total composition of maleic acid, and preferably from 8% to 20%.

6. A composition according to any of the preceding claims wherein said amine is according to the formula RR'R''N wherein R is a saturated or unsaturated, linear or branched alkyl group of 1 to 30 carbon atoms, preferably of 8 to 20 carbon atoms, more preferably of 6 to 16, most preferably of 8 to 14 and wherein R' and R'' are independently substituted or unsubstituted, linear or branched alkyl groups of from 1 to 4 carbon atoms, preferably of from 1 to 3 carbon atoms, and more preferably are methyl groups, or mixtures thereof.

7. A composition according to any of the preceding claims wherein said composition comprises from 0.01% to 20% by weight of the total composition of said amine, or mixtures thereof, preferably from 0.1% to 10%, and more preferably from 0.1% to 5% .

8. A composition according to any of the preceding claims wherein said composition further comprises another surfactant preferably an amine oxide according to the formula R1R2R3NO, wherein each of R1, R2 and R3 is independently a saturated or unsaturated, substituted or unsubstituted, linear or branched alkyl group of from 1 to 30 carbon atoms, or mixtures thereof.

9. A composition according to any of the preceding claims wherein said composition has a pH below 3, preferably a pH of from 0.1 to 2.5 and more preferably of from 0.1 to 2.

10. A process of treating a hard-surface soiled by limescale-containing stains, wherein an acidic liquid composition according to any of the preceding claims is applied in its neat form or in diluted form, onto said surface, then left to act onto said surfaces, and then removed by rinsing.

11. A process of treating a hard-surface soiled by limescale-containing stains, preferably bathroom-type and/or kitchen-type limescale-containing stains, wherein an acidic liquid composition comprising an amine according to the formula RR'R''N, wherein R is a saturated or unsaturated, substituted or unsubstituted, linear or branched alkyl group of from 1 to 30 carbon atoms, and wherein R' and R'' are independently saturated or unsaturated, substituted or unsubstituted, linear or branched alkyl groups of from 1 to 30 carbon atoms or hydrogen, is applied in its neat form or in diluted form, onto said surface, then left to act onto said surfaces, and then removed by rinsing.

12. The use, in an acidic limescale removal composition, of an amine according to the formula RR'R''N, wherein R is a saturated or unsaturated, substituted or unsubstituted, linear or branched alkyl group of from 1 to 30 carbon atoms, and wherein R' and R'' are independently saturated or unsaturated, substituted or unsubstituted, linear or branched alkyl groups of from 1 to 30 carbon atoms or hydrogen, to improve the greasy soap scum cleaning performance of said composition.