EP3418362A1

EP3418362A1 - Acidic cleaner comprising cationic cross-linked thickeners

Info

Publication number: EP3418362A1
Application number: EP18153658.2A
Authority: EP
Inventors: Deepak Ahirwal
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 2017-06-21
Filing date: 2018-01-26
Publication date: 2018-12-26

Abstract

Liquid acidic hard surface cleaning composition comprising cationic cross-linked thickening polymer provide a pleasing viscosity while also providing good limescale removal and limescale-soil deposit removal, especially on horizontal surfaces.

Description

TECHNICAL FIELD

The present invention relates to acidic liquid compositions for cleaning a variety of hard surfaces such as hard surfaces found in around the house, such as bathrooms, toilets, garages, driveways, basements, gardens, kitchens, etc. More specifically, the thickened compositions of the present invention deliver good limescale removal performance (i.e., removal of pure limescale deposits and/or limescale-containing soils).

BACKGROUND OF THE INVENTION

Acidic liquid compositions for cleaning limescale from hard-surfaces have been disclosed in the art. Limescale deposits, are formed due to the fact that tap water contains a certain amount of solubilised ions, which upon water evaporation eventually deposit as salts such as calcium carbonate on hard surfaces. The visible limescale deposits result in an unaesthetic aspect of the surfaces. The limescale formation and deposition phenomenon is even more acute in places where water is particularly hard. Furthermore, limescale deposits are prone to combination with other types of soils, such as soap scum or grease, and can lead to the formation of limescale-soil mixture deposits (limescale-containing soils). The removal of limescale deposits and limescale-containing soils is herein in general referred to as "limescale removal" or "removing limescale". For vertical and inclined surfaces, a challenge is to keep the acidic liquid composition on the surface sufficiently long in order to provide good limescale removal. This has been achieved by adding a thickener to increase the viscosity of the liquid composition, in order to provide improved cling of the composition to the vertical or inclined surface. However, acidic cleaning compositions remove limescale deposits and limescale-containing soils by decomposing the carbonate, contained within the limescale. A by-product of this decomposition is carbon dioxide, which is released as a gas. The heightened viscosity and foaming due to gas formation slows the migration of the acid to the interface between the liquid and the surface. As a result, efficacy of limescale removal for horizontal surfaces is reduced when the acidic liquid composition comprises a thickener.
Hence, a need remains for a thickened composition, which provides improved limescale removal efficacy, and improved limescale-soil deposit removal, for vertical and inclined surfaces, while also not inhibiting limescale removal for horizontal surfaces.
EP1509556 relates to thickened aqueous formulations containing cross-linked cationic polymers, novel homo- and copolymers their production and their use as thickeners for household formulations, especially for fabric softener applications. EP0395282 relates to aqueous acidic solutions which are thickened by cationic polymer, the polymer being added to the solution in the form of particles below 10 micron in size. WO2011/100405 relates to fabric and household hard surface treatment compositions comprising a mixture of cross-linked polyglycerol esters molecules each comprising at least two polyglycerol ester moieties, a non-crosslinker moiety; and a crosslinker moiety; and a carrier material. WO 2013/0683 87 A1 relates to a thickener which can be obtained by inverse emulsion polymerization of at least one water-soluble ethylenically unsaturated monomer comprising at least one cationic monomer, at least one ethylenically unsaturated associative monomer, where the temperature is kept constant during the inverse emulsion polymerization and is at least 40°C, and the activator is added after the inverse emulsion polymerization in order to obtain the thickness. WO2004/050815 A1 relates to aqueous compositions, preferably aqueous compositions comprising home- and/or copolymers. WO99/06455 A1 relates to thickening agents for acidic aqueous compositions.

SUMMARY OF THE INVENTION

The present invention relates to a liquid acidic hard surface cleaning composition having a pH of from 0.1 to 6.5 and at least 0.5 wt% of organic acid, wherein the composition further comprises a thickener, the thickener comprising a cationic cross-linked thickening polymer, wherein the cationic cross-linked thickening polymer comprises monomers of:
wherein: R₄ is hydrogen or methyl, preferably methyl; R₂ is hydrogen, or C₁ - C₄ alkyl, preferably hydrogen, R₃ is C₁ - C₄ alkyl, preferably C₂ alkyl; R₄, R₅, and R₆ are each independently chosen from hydrogen, or C₁ - C₄ alkyl, preferably C₁ - C₄ alkyl, more preferably methyl; X is chosen from -O-, or -NH-, preferably -O-; and Y is a halide, hydrogensulfate or methosulfate, preferably a halide, more preferably chloride; and comprises monomers of:
wherein: R₇ is from hydrogen or methyl, preferably hydrogen; R₈ is hydrogen or C₁ - C₄ alkyl, preferably hydrogen, and R₉ and R₁₀ are each independently hydrogen or C₁-C₄ alkyl, preferably hydrogen or methyl.

DETAILED DESCRIPTION OF THE INVENTION

The present compositions, comprising the crosslinked thickening polymer, provide sufficient cling to deliver good limescale removal on vertical and inclined surfaces, while also providing improved limescale removal on horizontal surfaces.
As defined herein, "essentially free of' a component means that no amount of that component is deliberately incorporated into the composition. Preferably, "essentially free of' a component means that no amount of that component is present in the composition.
As defined herein, "stable" means that no visible phase separation is observed for a premix kept at 25°C for a period of at least two weeks, or at least four weeks, or greater than a month or greater than four months, as measured using the Floc Formation Test, described in USPA 2008/0263780 A1 .
All percentages, ratios and proportions used herein are by weight percent of the composition, unless otherwise specified. All average values are calculated "by weight" of the composition, unless otherwise expressly indicated.
All ratios are calculated as a weight/weight level of the active material, unless otherwise specified. All measurements are performed at 25°C unless otherwise specified.
Unless otherwise noted, all component or composition levels are in reference to the active portion of that component or composition, and are exclusive of impurities, for example, residual solvents or by-products, which may be present in commercially available sources of such components or compositions.

The liquid acidic hard surface cleaning composition

The compositions according to the present invention are designed as hard surfaces cleaners. The compositions according to the present invention are liquid compositions (including gels) as opposed to a solid or a gas.
The liquid acidic hard surface cleaning compositions according to the present invention are preferably aqueous compositions. Therefore, they may comprise from 70% to 99% by weight of the total composition of water, preferably from 75% to 95% and more preferably from 80% to 95%.
The liquid compositions of the present invention are acidic. Therefore, they have a pH of less than 6.5. Preferably, the composition has a pH of from 1 to 6, more preferably from 2.0 to 2.5, still more preferably from 2.1 to 2.5, and most preferably from 2.1 to 2.4. The pH of the cleaning compositions is measured at 25°C.
Thus, the compositions comprise an acid system. Typically, the acid system may comprise any organic or inorganic acid well-known to those skilled in the art, or a mixture thereof. In preferred embodiments, the acid system comprises acids selected from the group consisting of: citric acid, formic acid, acetic acid, maleic acid, lactic acid, glycolic acid, succinic acid, glutaric acid, adipic acid, sulphamic acid, sulphuric acid, hydrochloric acid, phosphoric acid, nitric acid, methane sulphonic acid, oxalic acid and mixtures thereof, preferably acids selected from the group consisting of: citric acid, formic acid, acetic acid, lactic acid, phosphoric acid, oxalic acid and mixtures thereof.
In more preferred embodiments, the composition comprises an organic acid system, more preferably selected from the group consisting of: citric acid, formic acid, acetic acid, maleic acid, lactic acid, glycolic acid, succinic acid, glutaric acid, adipic acid, methane sulphonic acid, oxalic acid and mixtures thereof. More preferably, the organic acid system is selected from the group consisting of: citric acid, formic acid, oxalic acid, lactic acid and mixtures thereof.
The composition preferably comprises the organic acid system at a level of from 0.5 % to 15%, preferably from 0.5% to 10%, more preferably from 2% to 8%, most preferably from 4% to 7.5% by weight of the total composition.
Formic acid has been found to provide excellent limescale removal performance, in combination with improved surface safety, especially for surfaces which are prone to corrosion. For improved surface safety, especially of more delicate surfaces, the composition preferably comprises formic acid as part of the acid system. In order to achieve the desired pH, the compositions of the present invention may comprise from 0.01% to 15%, preferably from 0.5% to 10%, more preferably from 1% to 8%, even more preferably from 1% to 6%, still more preferably 1% to 4%, yet more preferably 1% to 3%, yet still more preferably 2% to 3% by weight of the total composition of formic acid.
Lactic acid can be used as part of the acid system, especially where antimicrobial or disinfecting benefits are desired. Such compositions may comprise up to 10% by weight of the total composition of lactic acid, preferably from 0.1% to 6%, more preferably from 0.2% to 4%, even more preferably from 0.2% to 3%, and most preferably from 0.5% to 2%.
The compositions of the present invention may comprise from 0.1 to 30%, preferably from 2% to 20%, more preferably from 3% to 15%, most preferably from 3% to 10% by weight of the total composition of acetic acid. Alternatively, the compositions of the present invention may comprise from 0.1 to 5%, preferably from 0.1% to 3%, more preferably from 0.1% to 2%, most preferably from 0.5% to 2% by weight of the total composition of acetic acid.
The compositions of the present invention may comprise from 0.1 to 30%, preferably from 1% to 20%, more preferably from 1.5% to 15%, most preferably from 2% to 10% by weight of the total composition of citric acid.
The compositions herein can comprise an alkaline material. The alkaline material may be present to trim the pH and/or maintain the pH of the compositions according to the present invention. Examples of alkaline material are sodium hydroxide, potassium hydroxide and/or lithium hydroxide, and/or the alkali metal oxides such, as sodium and/or potassium oxide or mixtures thereof and/or monoethanolamine and/or triethanolamine. Other suitable bases include ammonia, ammonium carbonate, choline base, etc. Preferably, source of alkalinity is sodium hydroxide or potassium hydroxide, preferably sodium hydroxide.
Typically the amount of alkaline material is of from 0.001 % to 20 % by weight, preferably from 0.01 % to 10 % and more preferably from 0.05 % to 3 % by weight of the composition.
Despite the presence of alkaline material, if any, the compositions herein would remain acidic compositions.
The compositions herein are thickened compositions. Thus, the liquid acidic hard surface cleaning compositions herein preferably have a viscosity of from 5 cps to 1000 cps at 10 s^-1, more preferably from 20 cps to 750 cps. For acidic cleaning compositions which are typically poured onto the surface from the container, the viscosity is preferably from 50 cps to 500 cps and most preferably from 100 cps to 350 cps at 10 s^-1 and 20°C. For acidic cleaning compositions which are typically sprayed onto the surface, the viscosity is preferably from 5 cps to 100 cps at 10 s^-1 and 20°C. The viscosity is measured with a Rheometer, model AR 1000 (Supplied by TA Instruments) with a 4 cm conic spindle in stainless steal, 2° angle (linear increment from 0.1 to 100 sec^-1 in max. 8 minutes).

Thickener:

The acidic cleaning composition comprises a thickener, wherein the thickener comprises a cationic cross-linked thickening polymer.
The cationic cross-linked thickening polymers comprises monomers of:
wherein:

R₁ is hydrogen or methyl, preferably methyl,
R₂ is hydrogen, or C₁ - C₄ alkyl, preferably hydrogen,
R₃ is C₁ - C₄ alkyl, preferably C₂ alkyl, R₄, R₅, and R₆ are each independently chosen from hydrogen, or
C₁ - C₄ alkyl, preferably C₁ - C₄ alkyl, more preferably methyl,
X is chosen from -O-, or -NH-, preferably -O-, and
Y is a halide, hydrogensulfate or methosulfate, preferably a halide, more preferably chloride;

R₇ is from hydrogen or methyl, preferably hydrogen;
R₈ is hydrogen or C₁ - C₄ alkyl, preferably hydrogen; and
R₉ and R₁₀ are each independently hydrogen or C₁-C₄ alkyl, preferably hydrogen or methyl.

Cross-linking can be achieved using any suitable cross-linking agent, such as N,N'-methylenebis(acrylamide) (MBA), tetraallylammonium chloride (TAAC), pentaerythritol triacrylate (PETIA), and mixtures thereof. Tetraallylammonium chloride (TAAC), N,N'-methylenebis(acrylamide) (MBA), and combinations oftetraallylammonium chloride (TAAC) with N,N'-methylenebis(acrylamide) (MBA) are preferred. The cross-linking agent is typically added at a level of from 50ppm to 1000 ppm, preferably from 300 ppm to 900 ppm.
The cationic cross-linked thickening polymer preferably has a molecular weight of at least 500,000 Daltons, preferably at least 1,000,000 Daltons, more preferably at least 2,000,000 Daltons. The cationic cross-linked thickening polymer typically has a broad polydispersity which makes the upper limit to the molecular weight less relevant for the performance of the polymer. Chain transfer agents can be used to increase the molecular weight of the cross-linked thickening polymer. Suitable chain transfer agents include mercaptanes, malic acid, lactic acid, formic add, isopropanol and hypophosphites, and mixtures thereof. Formic acid is preferred. The chain transfer agent can be added at a level of from 100 ppm to 5,000 ppm, preferably from 2,000 ppm to 2,500 ppm.
The cationic cross-linked thickening polymer can comprise at least 30 mol%, preferably at least 60 mol%, more preferably at least 85 mol% of monomers according to formula I.
Two or more monomer species are used, the resultant cationic cross-linked thickening polymer is a copolymer. The cationic cross-linked thickening polymer is a copolymer where combinations of monomers of formula I and formula II are used, in addition to the cross-linking agent and chain transfer agent. The monomers can be used in any suitable ratio. When the copolymer comprises combinations of monomers of formula I and formula II, the monomers are preferably present in a ratio of from 95:5 to 30:80, preferably from 90:10 to 60:40 of monomers of formula I to formula II. In preferred embodiments, the monomer of formula I is ethanaminium, N,N,N-trimethyl-2-((2-methyl-1-oxo-2-propenyl)oxy)-, chloride (CAS 26161-33-1), and the monomer of formula II is acrylamide (CAS 79-06-01) or methacrylamide (CAS 79-39-0). Suitable cationic cross-linked thickening copolymers include Flosoft® FS222, supplied by SNF Floerger.
The cationic cross-linked thickening polymer can comprise exclusively monomers of formula I and formula II.
The cationic cross-linked thickening polymer may be prepared as water in oil emulsions, wherein the cross-linked polymers are dispersed in the oil, preferably a mineral oil.
The cationic cross-linked thickening polymer can be present at a level of from 0.01% to 5.0% by weight of the total composition of the cationic cross-linked thickener, preferably from 0.1% to 2.5%, more preferably from 0.2% to 1.5% and most preferably from 0.3% to 0.75%. Comparative cationic cross-linked thickening polymers include a homopolymer where exclusively monomers of formula I are used, in addition to the cross-linking agent and chain transfer agent. Such cationic cross-linked thickening homopolymers are derived from monomers of ethanaminium, N,N,N-trimethyl-2-((2-methyl-1-oxo-2-propenyl)oxy)-, chloride (CAS 26161-33-1). Such comparative cationic cross-linked thickening homopolymers include Rheovis CDE, supplied by BASF.

Optional ingredients

The compositions according to the present invention may comprise a variety of optional ingredients depending on the technical benefit aimed for and the surface treated.
Suitable optional ingredients for use herein include other acids, preferably acetic acid and/or lactic acid and/or citric acid, chelating agents, nonionic surfactants, vinylpyrrolidone homopolymer or copolymer, polysaccharide polymer, radical scavengers, perfumes, solvents, other surfactants, builders, buffers, bactericides, hydrotropes, colorants, stabilizers, bleaches, bleach activators, suds controlling agents like fatty acids, enzymes, soil suspenders, brighteners, anti dusting agents, dispersants, pigments, and dyes.

Nonionic surfactant

The compositions of the present invention preferably comprise a nonionic surfactant, or a mixture thereof. This class of surfactants may be desired as it further contributes to cleaning performance of the hard surface cleaning compositions herein. It has been found in particular that nonionic surfactants strongly contribute in achieving highly improved performance on greasy soap scum removal.
The compositions according to the present invention may comprise up to 15% by weight of the total composition of a nonionic surfactant or a mixture thereof, preferably from 0.1% to 10%, more preferably from 0.5% to 5%, even more preferably from 1.0% to 3% by weight of the total composition.
Suitable nonionic surfactants for use 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 conveniently commercially available. Surfactants catalogs are available which list a number of surfactants, including nonionics.
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 (with the sum of e + p being at least 1). Preferably, 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 product of ethylene and/or propylene oxide with an alcohol having a straight alkyl chain comprising from 6 to 22 carbon atoms, wherein the degree of ethoxylation/propoxylation is from 1 to 15, preferably from 5 to 12 or mixtures thereof. Such suitable nonionic surfactants are commercially available from Shell, for instance, under the trade name Neodol® or from BASF under the trade name Lutensol®.

Vinylpyrrolidone homopolymer or copolymer

In order to provide improved shine over a wider range of surfaces, the compositions of the present invention may comprise a vinylpyrrolidone homopolymer or copolymer, or a mixture thereof. Typically, the compositions of the present invention may comprise from 0.01% to 5% by weight of the total composition of a vinylpyrrolidone homopolymer or copolymer, or a mixture thereof, more preferably from 0.05% to 3% and most preferably from 0.05% to 1%.
Suitable vinylpyrrolidone homopolymers for use herein are homopolymers of N-vinylpyrrolidone having the following repeating monomer:
wherein n (degree of polymerisation) is an integer of from 10 to 1,000,000, preferably from 20 to 100,000, and more preferably from 20 to 10,000.
Accordingly, suitable vinylpyrrolidone homopolymers ("PVP") for use herein have an average molecular weight of from 1,000 to 10,000,000, preferably from 5,000 to 1,000,000, and more preferably from 50,000 to 500,000.
Suitable vinylpyrrolidone homopolymers are commercially available from ISP Corporation, New York, NY and Montreal, Canada under the product names PVP K-15® (viscosity molecular weight of 10,000), PVP K-30® (average molecular weight of 40,000), PVP K-60® (average molecular weight of 160,000), and PVP K-90® (average molecular weight of 360,000). Other suitable vinylpyrrolidone homopolymers which are commercially available from BASF Cooperation include Sokalan HP 165®, Sokalan HP 12®, Luviskol K30®, Luviskol K60®, Luviskol K80®, Luviskol K90®; vinylpyrrolidone homopolymers known to persons skilled in the detergent field (see for example EP-A-262,897 and EP-A-256,696 ).
Suitable copolymers of vinylpyrrolidone for use herein include copolymers of N-vinylpyrrolidone and alkylenically unsaturated monomers or mixtures thereof.
The alkylenically unsaturated monomers of the copolymers herein include unsaturated dicarboxylic acids such as maleic acid, chloromaleic acid, fumaric acid, itaconic acid, citraconic acid, phenylmaleic acid, aconitic acid, acrylic acid, N-vinylimidazole and vinyl acetate. Any of the anhydrides of the unsaturated acids may be employed, for example acrylate, methacrylate. Aromatic monomers like styrene, sulphonated styrene, alpha-methyl styrene, vinyl toluene, t-butyl styrene and similar well known monomers may be used.
Particularly suitable N-vinylimidazole N-vinylpyrrolidone polymers for use herein have an average molecular weight range from 5,000 to 1,000,000, preferably from 5,000 to 500,000, and more preferably from 10,000 to 200,000. The average molecular weight range was determined by light scattering as described in Barth H. G. and Mays J. W. Chemical Analysis Vol 113,"Modern Methods of Polymer Characterization".
Such copolymers of N-vinylpyrrolidone and alkylenically unsaturated monomers like PVP/vinyl acetate copolymers are commercially available under the trade name Luviskol® series from BASF.
According to a very preferred execution of the present invention, vinylpyrrolidone homopolymers are advantageously selected.

Chelating agent

The compositions of the present invention may comprise a chelating agent or mixtures thereof, as a preferred optional ingredient. Chelating agents can be incorporated in the compositions herein in amounts ranging from 0% to 10% by weight of the total composition, preferably 0.01% to 5.0%, more preferably 0.05% to 1%.
Suitable phosphonate chelating agents to be used herein may include alkali metal ethane 1-hydroxy diphosphonates (HEDP), alkylene poly (alkylene phosphonate), as well as amino phosphonate compounds, including amino aminotri(methylene phosphonic acid) (ATMP), nitrilo trimethylene phosphonates (NTP), ethylene diamine tetra methylene phosphonates, and diethylene triamine penta methylene phosphonates (DTPMP). The phosphonate compounds may be present either in their acid form or as salts of different cations on some or all of their acid functionalities. Preferred chelating agents to be used herein are diethylene triamine penta methylene phosphonate (DTPMP) and ethane 1-hydroxy diphosphonate (HEDP). In a particularly preferred execution of the present invention, the chelating agent is selected to be ethane 1-hydroxy diphosphonate (HEDP). Such phosphonate chelating agents are commercially available from Monsanto under the trade name DEQUEST®.
Polyfunctionally-substituted aromatic chelating agents may also be useful in the compositions herein. See U.S. patent 3,812,044, issued May 21, 1974, to Connor et al. Preferred compounds of this type in acid form are dihydroxydisulfobenzenes such as 1,2-dihydroxy -3,5-disulfobenzene. A preferred biodegradable chelating agent for use herein is ethylene diamine N,N'- disuccinic acid, or alkali metal, or alkaline earth, ammonium or substitutes ammonium salts thereof or mixtures thereof. Ethylenediamine N,N'- disuccinic acids, especially the (S,S) isomer have been extensively described in US patent 4, 704, 233, November 3, 1987, to Hartman and Perkins . Ethylenediamine N,N'- disuccinic acids is, for instance, commercially available under the tradename ssEDDS® from Palmer Research Laboratories.
Suitable amino carboxylates to be used herein include tetra sodium glutamate diacetate (GLDA), ethylene diamine tetra acetates, diethylene triamine pentaacetates, diethylene triamine pentaacetate (DTPA), N- hydroxyethylethylenediamine triacetates, nitrilotri-acetates, ethylenediamine tetrapropionates, triethylenetetraaminehexa-acetates, ethanol-diglycines, propylene diamine tetracetic acid (PDTA) and methyl glycine di-acetic acid (MGDA), both in their acid form, or in their alkali metal, ammonium, and substituted ammonium salt forms. Particularly suitable amino carboxylates to be used herein are diethylene triamine penta acetic acid, propylene diamine tetracetic acid (PDTA) which is, for instance, commercially available from BASF under the trade name Trilon FS® methyl glycine di-acetic acid (MGDA), tetra sodium glutamate diacetate (GLDA) which is, for instance, commercially available from AkzoNobel under the trade name Dissolvine® GL.
Further carboxylate chelating agents to be used herein include salicylic acid, aspartic acid, glutamic acid, glycine, malonic acid or mixtures thereof.
The addition of a chelating agent, preferably HEDP, in the composition of the present invention provides an unexpected improvement in terms of limescale removal.

Solvent

The compositions of the present invention may further comprise a solvent or a mixture thereof, as an optional ingredient. Solvents to be used herein include all those known to those skilled in the art of hard-surfaces cleaner compositions. In a highly preferred embodiment, the compositions herein comprise an alkoxylated glycol ether (such as n-Butoxy Propoxy Propanol (n-BPP)) or a mixture thereof.
Typically, the compositions of the present invention may comprise from 0.1% to 5% by weight of the total composition of a solvent or mixtures thereof, preferably from 0.5% to 5% by weight of the total composition and more preferably from 1% to 3% by weight of the total composition.

Additional surfactant

The compositions of the present invention may comprise an additional surfactant, or mixtures thereof, on top of the nonionic surfactant already described herein. Additional surfactants may be desired herein as they further contribute to the cleaning performance and/or shine benefit of the compositions of the present invention. Surfactants to be used herein include anionic surfactants, cationic surfactants, amphoteric surfactants, zwitterionic surfactants, and mixtures thereof. Accordingly, the compositions according to the present invention may comprise up to 15% by weight of the total composition of another surfactant or a mixture thereof, on top of the nonionic surfactant already described herein, more preferably from 0.5% to 5%, even more preferably from 0.5% to 3%, and most preferably from 0.5% to 2%. Different surfactants may be used in the present invention including anionic, cationic, zwitterionic or amphoteric surfactants. It is also possible to use mixtures of such surfactants without departing from the spirit of the present invention.
Preferred surfactants for use herein are anionic and zwitterionic surfactants since they provide excellent grease soap scum cleaning ability to the compositions of the present invention.
Anionic surfactants may be included herein as they contribute to the cleaning benefits of the hard-surface cleaning compositions of the present invention. Indeed, the presence of an anionic surfactant contributes to the greasy soap scum cleaning of the compositions herein. More generally, the presence of an anionic surfactant in the liquid acidic compositions according to the present invention allows to lower the surface tension and to improve the wettability of the surfaces being treated with the liquid acidic compositions of the present invention. Furthermore, the anionic surfactant, or a mixture thereof, helps to solubilize the soils in the compositions of the present invention.
Suitable anionic surfactants for use herein are all those commonly known by those skilled in the art. Preferably, the anionic surfactants for use herein include alkyl sulphonates, alkyl aryl sulphonates, or mixtures thereof.
Particularly suitable linear alkyl sulphonates include C8 sulphonate like Witconate® NAS 8 commercially available from Witco.
Other anionic surfactants useful herein include salts (including, for example, sodium, potassium, ammonium, and substituted ammonium salts such as mono-, di- and triethanolamine salts) of soap, alkyl sulphates, alkyl aryl sulphates alkyl alkoxylated sulphates, C8-C24 olefinsulfonates, sulphonated polycarboxylic acids prepared by sulphonation of the pyrolyzed product of alkaline earth metal citrates, e.g., as described in British patent specification No. 1,082,179 ; alkyl ester sulfonates such as C14-16 methyl ester sulfonates; acyl glycerol sulfonates, alkyl phosphates, isethionates such as the acyl isethionates, N-acyl taurates, alkyl succinamates, acyl sarcosinates, sulfates of alkylpolysaccharides such as the sulfates of alkylpolyglucoside (the nonionic nonsulfated compounds being described below), alkyl polyethoxy carboxylates such as those of the formula RO(CH2CH2O)kCH2COO-M+ wherein R is a C8-C22 alkyl, k is an integer from 0 to 10, and M is a soluble salt-forming cation. Resin acids and hydrogenated resin acids are also suitable, such as rosin, hydrogenated rosin, and resin acids and hydrogenated resin acids present in or derived from tall oil. Further examples are given in "Surface Active Agents and Detergents" (Vol. I and II by Schwartz, Perry and Berch). A variety of such surfactants are also generally disclosed in U.S. Patent 3,929,678, issued December 30, 1975 to Laughlin, et al. at Column 23, line 58 through Column 29, line 23.
Suitable zwitterionic surfactants for use herein contain both basic and acidic groups which form an inner salt giving 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.
Some common examples of zwitterionic surfactants (i.e. betaine/sulphobetaine) are described in U.S. Pat. Nos. 2,082,275 , 2,702,279 and 2,255,082 .
For example Coconut dimethyl betaine is commercially available from Seppic under the trade name of Amonyl 265®. Lauryl betaine is commercially available from Albright & Wilson under the trade name Empigen BB/L®. A further example of betaine is Lauryl-immino-dipropionate commercially available from Rhodia under the trade name Mirataine H2C-HA®.
Particularly preferred zwitterionic surfactants for use in the compositions of the present invention are the sulfobetaine surfactants as they deliver optimum soap scum cleaning benefits.
Examples of particularly suitable sulfobetaine surfactants include tallow bis(hydroxyethyl) sulphobetaine, cocoamido propyl hydroxy sulphobetaines which are commercially available from Rhodia and Witco, under the trade name of Mirataine CBS® and Rewoteric AM CAS 15® respectively.
Amphoteric and ampholytic detergents which can be either cationic or anionic depending upon the pH of the system are represented by detergents such as dodecylbeta-alanine, N-alkyltaurines such as the one prepared by reacting dodecylamine with sodium isethionate according to the teaching of U.S. Pat. No. 2,658,072 , N-higher alkylaspartic acids such as those produced according to the teaching of U.S. Pat. No. 2,438,091 , and the products sold under the trade name "Miranol", and described in U.S. Pat. No. 2,528,378 . Additional synthetic detergents and listings of their commercial sources can be found in McCutcheon's Detergents and Emulsifiers, North American Ed. 1980.
Suitable amphoteric surfactants include the amine oxides. Examples of 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 Clariant, Stepan, and AKZO (under the trade name Aromox®). Other suitable amphoteric surfactants for the purpose of the invention are the phosphine or sulfoxide surfactants.
Cationic surfactants suitable for use in compositions of the present invention are those having a long-chain hydrocarbyl group. Examples of such cationic surfactants include the quaternary ammonium surfactants such as alkyldimethylammonium halogenides. Other cationic surfactants useful herein are also described in U.S. Patent 4,228,044 , Cambre, issued October 14, 1980.

The process of cleaning a hard-surface or an object

The cross-linked thickening polymers described herein are particularly useful in acidic cleaning compositions for processes for providing improved limescale removal, and improved limescale-soil deposit removal, especially on horizontal surfaces.
Such processes can comprise the steps of: applying the liquid acidic hard surface cleaning composition onto said hard-surface or said object; leaving said composition on said hard-surface or said object to act; optionally wiping said hard-surface or object and/or providing mechanical agitation, and then rinsing said hard-surface or said object.
The compositions according to the present invention are particularly suitable for treating hard-surfaces located in and around the house, such as in bathrooms, toilets, garages, on driveways, basements, gardens, kitchens, etc., and preferably in bathrooms. It is however known that such surfaces (especially bathroom surfaces) may be soiled by the so-called "limescale-containing soils". By "limescale-containing soils" it is meant herein any soil which contains not only limescale mineral deposits, such as calcium and/or magnesium carbonate, but also soap scum (e.g., calcium stearate) and other grease (e.g. body grease). By "limescale deposits" it is mean herein any pure limescale soil, i.e., any soil or stains composed essentially of mineral deposits, such as calcium and/or magnesium carbonate.
By "hard-surface", it is meant herein any kind of surfaces typically found in and around houses like bathrooms, kitchens, basements and garages, e.g., floors, walls, tiles, windows, sinks, showers, shower plastified curtains, wash basins, WCs, dishes, fixtures and fittings and the like made of different materials like ceramic, enamel, painted and un-painted concrete, plaster, bricks, vinyl, no-wax vinyl, linoleum, melamine, Formica®, glass, any plastics, metals, chromed surface and the like. The term surfaces as used herein also include household appliances including, but not limited to, washing machines, automatic dryers, refrigerators, freezers, ovens, microwave ovens, dishwashers and so on. Preferred hard surfaces cleaned with the liquid aqueous acidic hard surface cleaning composition herein are those located in a bathroom, in a toilet or in a kitchen, basements, garages as well as outdoor such as garden furniture, gardening equipments, driveways etc.
The objects herein are objects that are subjected to limescale formation thereon. Such objects may be water-taps or parts thereof, water-valves, metal objects, objects made of stainless-steel, cutlery and the like.
The preferred process of cleaning a hard-surface or an object (preferably removing limescale from said hard-surface or said object) comprises the step of applying a composition according to the present invention onto said hard-surface or object, leaving said composition on said hard-surface or object to act, preferably for an effective amount of time, more preferably for a period comprised between 10 seconds and 10 minutes, most preferably for a period comprised between 15 seconds and 4 minutes; optionally wiping said hard-surface or object with an appropriate instrument, e.g. a sponge; and then preferably rinsing said surface with water.
Even though said hard-surface or object may optionally be wiped and/or agitated during the process herein, it has been surprisingly found that the process of the present invention allows good limescale removal performance without any additional mechanical wiping and/or agitation action. The lack of need for additional wiping and/or mechanical; agitation provides an added convenience for the user of the compositions herein.
Moreover, the processes described herein allow good removal of limescale- soap mixture depositions (such as greasy soap scum) with only moderate mechanical wiping and/or agitation action.
The compositions of the present invention may be contacted to the surface or the object to be treated in its neat form or in its diluted form. Preferably, the composition is applied in its neat form.
By "diluted form", it is meant herein that said composition is diluted by the user, typically with water. The composition is diluted prior use to a typical dilution level of 10 to 400 times its weight of water, preferably from 10 to 200 and more preferably from 10 to 100. Usual recommended dilution level is a 1.2% dilution of the composition in water.
The compositions herein may be packaged in any suitable container, such as bottles, preferably plastic bottles, optionally equipped with an electrical or manual trigger spray-head.

Methods:

A) pH measurement:

The pH is measured on the neat composition, at 25°C, using a Sartarius PT-10P pH meter with gel-filled probe (such as the Toledo probe, part number 52 000 100), calibrated according to the instructions manual.

B) Limescale removal:

Limescale removal is measured using a gravimetric method quantifying the weight loss of a marble chip (calcium carbonate, 2.0 cm x 2.0 cm x 0.5 cm blocks of Carrara, supplied by Crombé Haachtsesteenweg 1465, 1130 Brussel) after immersion in the product.
The marble chip is thoroughly cleaned with demineralised water and put in a pre-heated oven (105°C) (WTC Binder Type Series M240 or IP20, temperature range 20-250°C. Precision ±0.75%) for 15 minutes. The marble chip is then taken out of the oven and left for 15 minutes in a constant humidity cabinet at 25°C, 70% RH (Climatic Control Cabinet from HERAEUS Belgium Type HC0033 (3302)). After 15 minutes of cooling down, each marble chip is weighed (initial weight) using an analytical balance (precision ±0.1mg).
A plastic cup (Ava papierwaren, model nr. 2 CR) is filled with 20 grams of test product. The marble chip is immersed in the cup for 5 minutes. The marble chip is then taken out of the cup and rinsed thoroughly with demineralised water. The chip is then dried in the oven at 105°C for 15 minutes and then transferred to the humidity cabinet for 15 minutes (25°C, 70%RH). After 15 minutes of cooling down, the marble chip is weighed (final weight). The weight lost (final weight - initial weight) represents the limescale removed in mg of Calcium carbonate. The test is repeated a total of 5 times and the result averaged. The results are presented as an index vs the reference (index 100).

EXAMPLES:

These following compositions were made comprising the listed ingredients in the listed proportions (active weight %). Example 1 is a composition of the present invention, comprising Rheovis CDE as the thickening polymer, while examples A to C are comparative compositions which comprised either chitosan, a linear cationic thickener, or Xanthan gum, an anionic thickener.

The relative limescale removale was assessed using the procedure described earlier.

Composition	Ex 1 of invention	Ex 2 (Comp)	Ex A (Comp)	Ex B (Comp)	Ex C (Comp)
	wt%	wt%	wt%	wt%	wt%
Citric acid	4.2	4.2	4.2	4.2	4.2
Formic acid	2.7	2.7	2.7	2.7	2.7
C9-C11 8E0¹	2.2	2.2	2.2	2.2	2.2
Sodium Hydroxide	0.25	0.25	0.25	0.25	0.25
Flosoft® FS222²	0.47	-	-	-	-
Rheovis® CDE³	-	0.73	-	-	-
Chitosan⁴	-	-	0.5	-	-
Xantham gum⁵	-	-	-	0.25	0.1
Perfume	0.2	0.2	0.2	0.2	0.2
Dyes	0.00781	0.00781	0.00781	0.00781	0.00781
Polyvinylpyrrolidone (PVP)⁶	0.025	0.025	0.025	0.025	0.025
Water	Balance up to 100	Balance up to 100	Balance up to 100	Balance up to 100	Balance up to 100
pH	2.2	2.2	2.2	2.2	2.2
Viscosity at 10s^-1	160	148	135	142	22
Limescale removal	230	193	188	100	185
(mg CaCO₃ removed - index vs. Ex B)

¹ Nonionic surfactant, sourced as Neodol® 91-8 from Shell.
² Cationic cross-linked thickener of use in the present invention, supplied by SNF Floerger
³ Cationic cross-linked thickener of use in the present invention, supplied by BASF
⁴ Cationic linear thickener supplied by i-chess chemicals Pvt Ltd, under the tradename Cee'san TH®
⁵ Kelzan T® is a Xanthan gum supplied by Kelco.
⁶ Polyvinylpyrrolidone, sourced as PVP K-60 from Ashland Inc.

As can be seen from the test results, the compositions comprising the cationic cross-linked thickener (examples 1 and comparative example 2) provide improved lime-scale removal, at similar viscosities, when compared to either non-cross-linked cationic thickener (chitosan) or Xantham gum (comparative examples A and B). Indeed, the inventive compositions provide improved limescale removal even when compared to compositions comprising lower levels of Xanthan gum, having a much lower viscosity (comparative example C).

Flosoft® FS222 is a cationic cross-linked thickening polymer comprising monomers of formula I and formula II, with at least 85 mol% of monomer of formula I. Rheovis® CDE is a cationic cross-linked thickening polymer which is a homopolymer of monomers of formula I. As can be seen from comparing the limescale removal of example 1 with that of comparative example 2, compositions comprising cationic cross-linked thickening polymers comprising both monomers of formula I and formula II provide further improved limescale removal, even at higher viscosities.

Examples 3 to 11 are further examples of compositions of the present invention.

Examples:	3	4	5	6	7	8*	9*	10	11
Acids
Formic acid	1	2.7	2.7	1	1	2.7	2.7	2.7	3
Acetic acid	1	0	1	1	1	0	0	0	0
Citric acid	1	1.7	4	1	1	1.7	1.7	4	0
Lactic acid	1	0	0	1	1	0	0	0	0

Surfactants
C9-C11 8E0¹	2.2	2.2	2.2	0	4	2.2	3	2.2	2

Thickener:
Flosoft FS222²	0.6	0.47	0.47	0.47	0.47	0	0	0.1	0.47
Rheovis CDE³	0	0	0	0	0	0.5	0.5	0	0

Surface modification polymer:
Polyvinylpyrrolidone (PVP)⁶	0.025	0.025	0.1	0.1	0.025	0.025	0.01	0.01	0.025

Misc.:
Perfume	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2
Dye	0.00781	0.00781	0.00781	0.00781	0.00781	0.00781	0.00781	0.00781	0.00781

Akaline Material:
KOH - to pH :	0	0	0	0	0	2.2	0	0	0
NaOH - to pH =	2.2	2.2	2.2	2.2	2.2	0	2.2	2.2	2.2
Water:	------------------------------ up to 100% ------------------------------

* Comparative

Formic acid, lactic acid and acetic acid are commercially available from Aldrich.
The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as "40 mm" is intended to mean "about 40 mm."

Claims

A liquid acidic hard surface cleaning composition having a pH of from 0.1 to 6.5 and at least 0.5 wt% of organic acid, wherein the composition further comprises a thickener, the thickener comprising a cationic cross-linked thickening polymer,
wherein the cationic cross-linked thickening polymer comprises monomers of:
wherein:
R₁ is hydrogen or methyl, preferably methyl,

R₂ is hydrogen, or C₁ - C₄ alkyl, preferably hydrogen,

R₃ is C₁ - C₄ alkyl, preferably C₂ alkyl,

R₄, R₅, and R₆ are each independently chosen from hydrogen, or C₁ - C₄ alkyl, preferably C₁ - C₄ alkyl, more preferably methyl,

X is chosen from -O-, or -NH-, preferably -O-, and

Y is a halide, hydrogensulfate or methosulfate, preferably a halide, more preferably chloride;
and comprises monomers of:
wherein:
R₇ is from hydrogen or methyl, preferably hydrogen,

R₈ is hydrogen or C₁ - C₄ alkyl, preferably hydrogen, and
R₉ and R₁₀ are each independently hydrogen or C₁-C₄ alkyl, preferably hydrogen or methyl.
wherein the composition has a viscosity of from 5 cps to 1000 cps at 10 s^-1.
The composition according to claim 1, wherein the cationic cross-linked thickening polymer comprises at least 30 mol%, preferably at least 60 mol%, more preferably at least 85 mol% of monomers according to formula I.
The composition according to claim 1, wherein the monomers are present in a ratio of from 95:5 to 30:80, preferably from 90:10 to 60:40 of monomers of formula I to formula II.
The composition according to any of claims 1 or 2, wherein the monomer of formula II is acrylamide (CAS 79-06-01) or methacrylamide.
The composition according to any preceding claim, wherein the monomer of formula I is ethanaminium, N,N,N-trimethyl-2-((2-methyl-1-oxo-2-propenyl)oxy)-, chloride.
The composition according to any preceding claims, wherein the cationic cross-linked thickening polymer is cross-linked using a cross-linking agent selected from the group consisting of: N,N'-methylenebis(acrylamide) (MBA), tetraallylammonium chloride (TAAC), pentaerythritol triacrylate (PETIA), and mixtures thereof, preferably from the group consisting of: tetraallylammonium chloride (TAAC), N,N'-methylenebis(acrylamide) (MBA), and mixtures thereof.
The composition according to any preceding claims, wherein the cationic cross-linked thickening polymer has a molecular weight of greater than 500,000 Daltons, preferably greater than 1,000,000 Daltons, more preferably greater than 2,000,000 Daltons.
The composition according to any of the preceding claims, wherein said composition comprises from 0.01% to 5.0% by weight of the total composition of the cationic cross-linked thickener, preferably from 0.1% to 2.5%, more preferably from 0.2% to 1.5% and most preferably from 0.3% to 0.75%.
The composition according to any of the preceding claims, wherein said composition has a pH of from 1 to 6, preferably 2.0 to 2.5, more preferably from 2.1 to 2.5, even more preferably 2.1 to 2.4.
The composition according to any preceding claim, wherein said composition comprises the organic acid at a level of from 0.5 % to 15%, preferably from 0.5% to 10%, more preferably from 2% to 8%, most preferably from 4% to 7.5% by weight of the total composition.
The composition according to any of the preceding claims, wherein the composition comprises an organic acid selected from the group consisting of: citric acid, formic acid, acetic acid, maleic acid, lactic acid, glycolic acid, succinic acid, glutaric acid, adipic acid, methane sulphonic acid, oxalic acid and mixtures thereof.
The composition according to any of the preceding claims, wherein said composition further comprises an alkaline material, preferably selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, the alkali metal oxides such, as sodium and/or potassium oxide or mixtures thereof, monoethanolamine, triethanolamine, ammonia, ammonium carbonate and, choline base and mixtures thereof, most preferably sodium hydroxide or potassium hydroxide.
The composition according to any of the preceding claims, wherein said composition further comprises one or more nonionic surfactant, preferably a nonionic surfactant which is the condensation product of ethylene and/or propylene oxide with an alcohol having a straight alkyl chain comprising from 6 to 22 carbon atoms, wherein the degree of ethoxylation/propoxylation is from 1 to 15, preferably from 5 to 12 or mixtures thereof.