WO2002090477A2

WO2002090477A2 - Liquid abrasive cleaning compositions

Info

Publication number: WO2002090477A2
Application number: PCT/EP2002/004581
Authority: WO
Inventors: Alessia Gambarini; Rita Lodola; Paolo Seresini
Original assignee: Hindustan Lever Ltd; Unilever NV
Current assignee: Hindustan Unilever Ltd; Unilever NV
Priority date: 2001-05-04
Filing date: 2002-04-25
Publication date: 2002-11-14
Anticipated expiration: 2003-11-04
Also published as: AU2002310882A1; WO2002090477A3; AU2002310882A8

Abstract

The invention concerns aqueous liquid abrasive cleaning compositions comprising at least 3, but less than 10% mineral abrasive and a lamellar phase structuring system comprising 2-12% of a mixture of nonionic and synthetic anionic surfactants wherein at least 40% of the anionic surfactant consists of alkyl-(EO)n-sulphate salt with n having a value of 1-10 and the ratio of synthetic anionic surfactant to nonionic surfactant is between 4:1 and 1:2.

Description

LIQUID ABRASIVE CLEANING COMPOSITIONS

Field of the invention

The invention relates to aqueous liquid compositions which include an abrasive and a detergent surfactant and are suitable for hard surface cleaning.

Background of the invention

Liquid abrasive cleaning compositions are well known in the art and typically comprise a combination of detergent surfactants, particularly anionic and nonionic surfactants, which together form a lamellar phase and thereby cause thickening of the liquid. The lamellar phase structured liquid acts as a suspending system to keep the solid abrasive in a stable suspension. In most cases an electrolyte is added to the composition to further improve the stability of the suspension.

The surfactant systems used in liquid abrasive cleaning compositions may include any one of a range of anionic surfactants such as the alkalimetal, ammonium or alkanol- ammonium alkylbenzene sulphonates (LAS) , primary and secondary alkyl sulphates (PAS and SAS) , dialkylmono- and disulphosuccinate esters. In EP-A-0 301 885 alkyl- (EO)_n-sulphate salts (n=l-10) are mentioned as one of the range of possible anionic surfactants in a composition comprising 25-70% mineral abrasive. Typically used nonionic surfactants are long chain aliphatic alcohol ethoxylates and amine oxides. Typical abrasive materials include minerals such as calcite and dolomite or other materials of relatively high density and sufficient hardness.

A well-known problem with liquid abrasive cleaners is their tendency to leave residues of solid abrasive on the cleaned surface, which are difficult to rinse away. Although wide ranges of abrasives content are quoted in the patent literature, ranging from less than 1% to 80% or higher, for the normal creamy liquid abrasive cleaner the practical abrasive content is generally considered to be at least 15% or even 20% and ranges up to 50%. Lower abrasive contents are generally considered to compromise on cleaning ability on tough and strongly adhering soils .

Organic solvents have been used in an attempt to further improve the cleaning capabilities of liquid abrasive cleaners. Thus, EP-A-0 336 651 describes such compositions containing a wide range of organic solvents with examples as diverse as 2- butoxyethanol, pine oil and limonene. The compositions all require colloidal aluminium oxide thickener to obtain a stable suspension. They preferably contain 20-40%, particularly 30%, of abrasive. A similar composition is described in EP-A-0 335 471 comprising 1.8-4.5% of a grease-removal solvent and 10-60% of an insoluble abrasive. A wide range of anionic surfactants is mentioned for the surfactant system, the preferred ones being fatty acid soap and PAS. Another similar composition is described in EP-A-0 329 209 comprising 2-10% of surfactant 1-10% of a non or sparingly water-soluble solvent. The surfactant is preferably a mixture of LAS and LES in a 1:1 to 4:1 ratio. The amount of abrasive is quoted to be 5-50%, but the examples all show 30%. In EP-A-0 126 545 combinations of terpenes and benzyl alcohol are used in liquid abrasive cleaning compositions containing up to 50% insoluble abrasive. In EP-A-0 269 178 terpenes are used in liquid abrasive cleaning compositions which optionally contain another organic solvent such as diethylene glycol monoalkyl ethers, or preferably benzyl alcohol.

In WO 97/47715, /47725 and /47726 several variations of cleaning compositions are described, all of which comprise: - up to 20% of a nonionic surfactant;

- up to 20 or 30% of a linear alkylbenzene sulphonate surfactant;

- 0.1-10% of an abrasive, preferably amorphous silica;

- from 0.02 up to 6, 8 or 15% of a water-insoluble organic compound selected from perfumes, essential oils and hydrocarbons, typically 1.5% or more;

- up to 15% or even 20% of a co-surfactant, which may be a (poly) ethylene glycol, (poly)propylene glycol or alkyl ether thereof. These compositions are particularly geared to the removal of greasy and oily soil and do not appear to have general purpose cleaning capability comparable to standard liquid abrasive cleaners . Similar compositions are described in WO 97/41204 comprising up to 20% of PAS and/or LES, up to 30% of ethoxylated alcohol nonionic surfactant, 1-30% of a co-surfactant being glycerol or mono-or polyethylene glycol or mono or polypropylene glycol 0.6- 10% of a perfume or water insoluble hydrocarbon having 6-18 carbon atoms, 0.1-10% abrasive and some other components.

Organic solvents are expensive components and primarily improve the performance on oily and fatty soils. Furthermore, organic solvents tend to decrease the stability of the suspension and it can be seen from the examples mentioned above that often complicated solvent mixtures in combination with extra thickening agents need to be used.

There is, therefore, a need to improve the performance of abrasive compositions in such a manner that the overall level of abrasive can be reduced so as to improve rinsing properties and reduce the possibility of surface damage by the abrasive, while at the same time maintaining cleaning performance on a large variety of soils without the need to use an organic solvent.

Brief description of the invention

It has now been found that liquid abrasive cleaning compositions comprising at least 3% but less than 10% mineral abrasive in combination with a surfactant system comprising an anionic surfactant and a nonionic surfactant provide excellent cleaning on a large variety of soils, including tough and strongly adhering soils, provided that the anionic surfactant comprises a substantial amount of alkyl- (EO)_n-sulphate salt.

Detailed description of the invention

All percentages given herein are by weight, calculated on the total composition, unless specifically indicated otherwise.

Thus, the invention provides aqueous liquid abrasive cleaning compositions comprising at least 3% but less than 10% mineral abrasive and a lamellar phase structuring system comprising 2- 12% of a mixture of nonionic and synthetic anionic surfactants wherein at least 40% of the anionic surfactant consists of alkyl- (EO)_n-sulphate salt with n having a value of 1-10.

The synthetic anionic surfactant or surfactants of the lamellar phase surfactant structuring system comprise the alkali metal, ammonium or alkanolammonium salts of the well known organic sulphuric acid esters and sulphonic acids having in the molecular structure a branched or straight chain alkyl group containing 8-22 C atoms or an alkylaryl group containing 6-20 C atoms in the alkyl part. Sodium and potassium salts are particularly preferred as are the surfactants in which the alkyl group is 9-18 carbon atoms.

The ethoxylated alkyl sulphate salts, which are conveniently, prepared from the corresponding ethoxylated alkohols. Commercial ethoxylated alkohols are mostly mixtures of components with different degrees of ethoxylation and may even contain a minor proportion of unethoxylated alcohol. Thus, in practice commercially mixtures of ethoxylated alkyl sulphate may contain varying amounts of unethoxylated alkyl sulphate. However, as outlined above, ethoxylated alkyl sulphate salts having at least one ethoxy group per alkyl- (EO)_n-sulphate ion make up at least 40% of the total anionic surfactant. The number of ethoxy groups per alkyl- (EO)_n-sulphate ion should be at least 1 and at most 10, preferably at most 5. Preferably the average number of ethoxylation (including any unethoxylated sulphate) is 0.5-2. The alkyl groups are primary or secondary and contain 8-22 carbon atoms, preferably 9-18, more preferably 9-15.

The amount of ethoxylated alkyl sulphate (alkyl- (EO)_n-sulphate) is preferably at least 60% of the total amount of synthetic anionic surfactant, more preferably at least 70% or even 80% and may constitute the only synthetic anionic surfactant. Preferably no other anionic surfactant is present beside the ethoxylated alkyl sulphate than the corresponding unethoxylated alkyl sulphate. The nonionic surfactant or surfactants may be chosen from those, which are well known in the art to be able to form part of a lamellar phase structuring system. Particularly useful are compounds produced by the condensation of simple alkylene oxides, which are hydrophilic in nature, with an aliphatic or alkyl-aromatic hydrophobic compound having a reactive hydrogen atom. The length of the hydrophilic or polyoxyalkylene chain, which is attached to any particular hydrophobic group, can be readily adjusted to yield a compound having the desired balance between hydrophilic and hydrophobic elements. Aliphatic alcohol ethoxylates having 8-22 (preferably 8-16, more preferably 9-16) carbon atoms in the aliphatic group and 2-10 ethoxy groups are prime examples of this group of nonionic surfactants. Another useful group of nonionic surfactants are the tertiary amine oxides of structure RRRN0, where one R is an alkyl group of 8 to 20 carbon atoms and the other R's are each alkyl or hydroxyalkyl groups of 1 to 3 carbon atoms, e.g. dimethyldodecylamine oxide. Aliphatic alcohol ethoxylates are especially preferred as nonionic surfactants.

The total amount of synthetic anionic surfactant is 1.5-7.0%, preferably, 2.0-6.0%, more preferably 3.0-5.0%. The total amount of nonionic surfactant is 0.5-5.0%, preferably 1.0-4.0%, more preferably 1.2-3.3%. The ratio of synthetic anionic surfactant to nonionic surfactant is between 4:1 and 1:2, preferably between 3:1 and 2:3, more preferably between 2:1 and 1:1. The amount of abrasive in the cleaning compositions according to the invention is preferably at least 4%, but at most 9%, more preferably at most 8%. Preferred abrasives have a Moh hardness of below 6, but above 1, although higher hardness abrasives can be employed for specialist applications. Preferably the hardness is at least 2.

Suitable inorganic abrasives can be selected zeolites, silica's, silicates, carbonates and alumina's. Preferred abrasives are: calcium carbonate (e.g. as calcite) , mixtures of calcium and magnesium carbonates (e.g. as dolomite), zeolite, alumina, hydrated alumina, feldspar, talc and silica. Calcite and dolomite and mixtures thereof optionally with lower amounts of amorphous silica, are particularly preferred due to their low cost and good abrasive properties.

Preferred weight average particle sizes for the abrasives fall in the range 0.5-500 microns, with values of 10-100 microns being particularly preferred. In this range an acceptable compromise between good cleaning behaviour and low substrate damage is achieved. Nevertheless, for silica to be used in combination with calcite and/or dolomite an average particle size in the range of 100-500 microns is very suitable as well.

The compositions according to the invention preferably have pH between 5 and 14, more preferably at least 7. An alkaline pH improves the cleaning properties, particularly on fatty soils and pH between 8 and 13 are very suitable.

To⁷ further improve the stability and suspending properties of the lamellar phase structuring system it is customary to include electrolyte and a number of electrolytes are known to be suitable for this purpose. Alkali metal hydroxides, carbonates and silicates are suitable because they are also useful for bringing the pH of the composition in the alkaline region. The amount of electrolyte is preferably 3-12%, more preferably 5-10%. The electrolyte suitably includes a certain amount (preferably 0.1% or more) of potassium ion e.g. as potassium carbonate. Other suitable electrolytes include alkali metal chlorides. Preferably no other electrolytes are present than alkalimetal chlorides, carbonates and hydroxydes

To further improve the stability of the suspension the compositions according to the invention optionally comprise a fatty acid or fatty acid mixture, preferably in an amount of 0.5-3%, more preferably 0.8-2.0%.

Furthermore, the- compositions according to the invention may optionally comprise a minor amount of a thickening polymer. Suitable polymers are high molecular weight products, i.e. having a molecular weight of at least 50,000 preferably at least 100,000 or even 500,000 or more. Suitable polymers are to be found among the polycarboxylate type polymers, such as various acrylate, methacrylate and maleic anhydride homo- polymers and copolymers which generally have a molecular weight of 500,000 or more, often well over 1000,000, and various polysaccharides and modified polysaccharides, such as carboxy- methylcelluloses, hydroxyethyl cellulose, hydroxypropyl- methylcellulose, carrageen, alginate, tragacanth gum, locust bean gum, guar gum, xanthan gum. The polymer is used in an amount to provide the composition with the desired rheological properties. Typically the amount is 0.05-1%. Very suitable are synthetic polycarboxylate polymers e.g. hydrophobically modified emulsion polymers and carbomers (solid powdered polyacrylic acids). Suitable polymers include: ACUSOL HASE and ASE series such as 820, 823 and 842; POLYGEL/NEUTRAGEL series such as W30, DA, DS, DR and DB; RHEOVIS series such as CRX

CARBOPOL series such as Aqua 30, ETD 2690, ETD 2691, ETD 2623, EZ-1, EZ-2, EP-1, LNP-3, 663, 664, 674, 674, 1610, 1621, 1622 and 1623; PEMULEN Series such as TR1 and TR2; STRUCTURE 2001, 3001; ALCOGUM SL-70 and SL-78.

ACUSOL is a trademark of Rohm & Haas; CARBOPOL and PEMULEN are trademarks of B F Goodrich;

POLYGEL and NEUTRAGEL are trademarks of Sigma 3V;

RHEOVIS is a trademark of Ciba Specialities;

STRUCTURE is a trademark of National Starch & Chemical Co.;

ALCOGUM is a trademark of Alco.

Inorganic thickeners, such as various kinds of thickening clay minerals and silica are preferably absent.

Because of the excellent cleaning properties of surfactant mixture with the ethoxylated alcohol sulphate in combination with the abrasive, the compositions according to the invention do not require an organic solvent. Although a minor amount of solvent may optionally be present the amount is kept below 5%, preferably below 2%, more preferably below 1%. If present, such solvents are normally chosen from C1-C4 alkanols, C2-C4 glycols and ethylen-, diethylene-, propylene- and dipropylene glycol ethers with C1-C5 alkyl groups. Most preferably no organic solvent is present at all. The compositions according to the invention may further comprise optional components to further enhance their properties in use, such as builders, antifoams, preservatives, antimicrobials, bleaching agents, etc.

They may also comprise components to enhance their consumer appeal such as colorants, pigments and particularly perfume. The amount thereof will generally not exceed 1% or even 0.5% for each of them.

Satisfactory "low abrasives content" liquid abrasive cleaning compositions according to the invention have such fluid flow characteristics that they are stable suspensions when not in use, but thin enough to be poured from the packaging container and spread on the soiled surface without appearing thin and watery.

Particularlly preferred compositions have the following composition:

Calcite (average particle size 30-65μm) 4-8% C12-13 alkyl-lEO sulphate Na salt 3-5%

C14-15 alcohol-5EO ethoxylate 1.5-3% Priolene TM (fatty acid mixture) 0.8-2%

Polyacrylate thickener (Acusol 823™) 0.1-0.4%

Na carbonate 7-9%

K carbonate 0.2-0.7% Water Example :

A stable liquid abrasive cleaning composition having excellent cleaning properties on a variety of soils had the following composition:

Calcite (average particle size 30-65um) 5^ C₁₂-₁₃ alkyl-lEO sulphate Na salt 4^ Ci₄-i₅ alcohol-5EO ethoxylate 2. ■ J2O- Priolene (fatty acid mixture) 1. .4%

Polyacrylate thickener (Acusol 823 TM) 0. .25% Na carbonate 8% K carbonate 0. 4% Silicone antifoam 0. ,06% Ti0₂ 0. 45% Perfume 0. 3% Water to 100%

Claims

Aqueous liquid abrasive cleaning compositions comprising a mineral abrasive and a lamellar phase structuring system comprising a mixture of nonionic and synthetic anionic surfactants characterised in that: it comprises at least 3 but less than 10% abrasive; the mixture of nonionic and synthetic anionic surfactants is present in an amount of 2-12%; at least 40% of the anionic surfactant consists of alkyl- (EO)_n-sulphate salt with n having a value between 1-10; the ratio of synthetic anionic surfactant to nonionic surfactant is between 4:1 and 1:2

Cleaning composition according to claim 1 characterised in that the amount of abrasive is 4-9%.

Cleaning composition according to claims 1-2 characterised in that the abrasive is chosen from calcium carbonate, mixtures of calcium and magnesium carbonates, zeolite, alumina, hydrated alumina, feldspar, talc and silica and has a particle size of 10-100 micron.

Cleaning composition according to claim 3 characterised in that the abrasive is chosen from calcite and dolomite and the composition has pH of at least 7.

Cleaning composition according to claims 1-4 characterised in that the total amount of synthetic anionic surfactant is 1.5-7% and the amount of nonionic surfactant is 0.5-5%.

6. Cleaning composition according to claim 5 characterised in that the ratio of synthetic anionic to nonionic surfactant is between 3:1 and 2:3.

7. Cleaning composition according to claims 1-6 characterised in that the amount of ethoxylated alkyl sulphate is at least 70% of the total amount of synthetic anionic surfactant.

8. Cleaning composition according to claims 1-6 characterised in that the nonionic surfactant is an ethoxylated aliphatic alcohol having 8-22 carbon atoms in the aliphatic group and 2-10 ethoxy groups.

9. Cleaning composition according to claims 1-8 characterised in that it comprises 3-12% of an electrolyte.

10. Cleaning compositions according to claim 9 characterised in that the electrolyte comprises potassium ion and/or alkali metal chlorides and no other electrolytes than alkalimetal chlorides, carbonates and hydroxydes .

11. Cleaning composition according to claims 1-10 characterised in that it comprises 0.5-3% of a fatty acid.

12. Cleaning composition according to claims 1-11 characterised in that it comprises 0-2% of an organic solvent chosen from C1-C4 alkanols, C2-C4 glycols and ethylen-, diethylene-, propylene- and dipropylene glycol ethers with C1-C5 alkyl groups .

3. Cleaning composition according to claims 1-11 characterised in that it comprises no organic solvent.