HUP0500857A2 - Abrasive hard surface cleaning compositions - Google Patents

Description

by rinsing.

FOOD SHOP

101380-2227Α TF

I Abrasive product for cleaning hard surfaces

The present invention relates to compositions for cleaning hard surfaces which contain an abrasive. More particularly, the present invention relates to compositions for cleaning hard surfaces which are effective in removing limescale and rust.

Background of the invention

Abrasive compositions for cleaning hard surfaces are well known in the art. Until a few years ago, such compositions were only available in powder form, but in the last decade liquid compositions have become much more popular. These compositions are easy to dispense creamy liquids that are much more appealing to consumers both tactilely and visually. However, these compositions are much more expensive than powders.

Most of these preparations are alkaline and therefore very effective in removing most dirt and grease deposits. However, they are only moderately effective in removing limescale and rust stains in toilets and bathrooms. Acid preparations have been developed for this purpose, which are much more effective in removing limescale and rust stains. These preparations may contain one or more organic and/or inorganic acids. Oxalic acid is mainly used for rust removal.

US Patent No. 5,460,742 describes acidic cleaning compositions. These are thixotropic liquids containing 5-50% of an abrasive, an amphoteric and nonionic surfactant, and a hydrated aluminosilicate thickener (thickening clay).

US Patent No. 3,579,456 discloses pourable acidic liquid detergents containing up to 60% abrasive, up to 10% polyvalent organic acid, e.g. oxalic acid, an anionic detergent, an ammonium zwitterionic detergent.

U.S. Patent No. 3,214,380 discloses similar compositions containing oxalic acid and a flint abrasive.

US Patent No. 4,561,993 discloses abrasive cleaning agents in the form of thixotropic liquids containing up to 20% mineral acid, up to 2.5% surfactant, which may not be anionic, up to 12% precipitated silica suspending agent and up to 15% abrasive.

US Patent No. 5,076,955 discloses a viscous, liquid, abrasive cleaning composition comprising an anionic surfactant, alumina and silicone oil. These also contain alkaline materials such as sodium hydroxide and sodium carbonate which are required in the manufacturing process.

JP-A-53139606 describes acidic cleaning agents which are viscous liquids and contain a mineral or organic acid and clay as a thickening agent. They may also contain an abrasive.

WO 01/27236 describes detergents which are acidic or neutral and which can be used for a variety of cleaning purposes, including machine dishwashing and as a detergent in bathrooms and restrooms. They contain inorganic compounds in the form of nanoparticles (1200 nm). These compounds are not capable of exerting an abrasive effect, but that is not their purpose. Furthermore, the composition is thixotropic, meaning that once it has set, it can be transformed into a gel-like, pourable liquid by shaking.

Many other acidic rust remover compositions are known in the art. Many of them are in powder form and may contain an abrasive component; others are liquids which may or may not be thickened to increase viscosity, but they do not contain an abrasive and only remove rust or scale by dissolving.

There is a need for a rust and scale removal product that has the advantages of liquid abrasive cleaners, including ease of dosing and a suitable sensory and visual appearance, but which is more economical in use and is able to remain in contact with the stain for a longer period of time after application to the stain—especially on an inclined or vertical surface—and thus provide chemical or solvent removal of the stain.

Subject matter of the present invention

In our work, we have found that aqueous acidic abrasive compositions suitable for cleaning hard surfaces can be prepared in the form of pastes, which are excellent for removing a wide variety of dirt and stains, including limescale and rust stains, combining a mechanical effect (abrasive effect) and a chemical effect/solvent effect. These pastes are easy to apply in the required quantity, making them economical to use.

Accordingly, the present invention provides an aqueous acidic cleaning composition having a paste-like consistency and comprising an abrasive, an acid, an anionic surfactant capable of forming a structured liquid with dilute acid, and optionally an acid-stable thickener.

The present invention also provides a method for removing rust or limescale stains from hard surfaces, which comprises applying the paste to the stain.

Detailed description of the invention

All percentages in the specification are by weight unless otherwise indicated.

As mentioned above, the acidic cleaning compositions of the invention are in the form of pastes. They are therefore highly viscous, sludge-like liquids. The pastes can be characterized by having a plateau viscosity of >1000 Pa s, preferably >10,000 Pa s, at low shear stress (<10 Pa), and a pronounced shear weakening at shear stresses of 1000 Pa or higher, preferably 200 Pa and above, more preferably 100 Pa or even 50 Pa and above. A useful paste has a viscosity of at least 0.1 Pa-s, preferably at least 0.2 Pa-s, more preferably at least 1 Pa-s, even more preferably at least 2 or even 5 Pa-s at a shear stress of 100 Pa.

The pastes according to the invention are acidic and have a pH value between 0 and 3, preferably 2.5 or less, more preferably 2 or even 1 or less. Accordingly, the pastes contain a mineral and/or organic acid in an amount sufficient to obtain the appropriate pH, generally 3-25% by weight, preferably at least 5%, calculated on the basis of the liquid phase (this can be determined in the present invention by deducting the weight of the abrasive from the total weight of the composition). The pastes preferably contain at least one mineral acid (inorganic acid), suitable examples of which are hydrochloric acid, sulfuric acid, sulfamic acid and phosphoric acid, preferably in an amount of 5% or more of the liquid phase. Sulfuric acid and sulfamic acid are particularly preferred. The composition may also contain up to 15% of the liquid phase of an organic acid, in particular di- or polycarboxylic acid. Oxalic acid and citric acid are suitable examples.

The pastes of the invention contain from 20 to 75% of the total composition of a solid particulate abrasive, preferably from 30 to 65%, more preferably at least 40%. Suitable abrasives have a Mohs hardness of 7 or less, but preferably above 1. Preferably the hardness is at least 2.

Suitable abrasives are stable in the acidic environment provided by the composition and may be selected from the following: inorganic abrasives such as silicas, silicates, aluminosilicates, aluminas, perlites, pumice and gypsum; organic polymeric abrasives such as polyethylene, polycarbonate, polyurethane, polystyrene, polypropylene, polyethylene terephthalate, polymethyl methacrylate and nylon; and natural abrasives such as ground walnut shells; and mixtures thereof. A special class of abrasives are those inorganic salts which are sparingly soluble in water and are used in amounts above their saturation solubility. Suitable salts in this class include sodium tripolyphosphate, sodium tetraborate and potassium sulfate.

Preferred abrasives include aluminosilicates, alumina, hydrated alumina, feldspar and silica. Particularly preferred are feldspar and silica, and combinations of any of these with gypsum, wherein the feldspar and/or silica constitute at least 25% of the abrasive mixture.

Suitable weight average particle sizes for abrasives are in the range of 0.5 to 500 pm. In this range, an acceptable balance can be maintained between good cleaning performance and low substrate damage. The weight average particle size is preferably 5 to 100 pm, more preferably 10 to 50 pm.

In addition, the pastes of the invention contain an anionic surfactant which is suitable for forming a structured fluid with the acidic aqueous phase. The structured fluid is capable of providing a stable suspension of the abrasive in the fluid.

A suitable class of anionic surfactants are the organosulfur monoesters and sulfonic acids which contain in the molecular structure a straight or branched chain amino group of 8-22 carbon atoms or an alkylaryl group having 6-20 carbon atoms in the alkyl portion. Sulfonates are particularly preferred, and the following are even more preferred:

- alkylbenzene sulfonates in which the alkyl group contains 6-20 carbon atoms and is preferably straight chain;

- alkanesulfonates, preferably secondary alkanesulfonates, more preferably those in which the alkyl chain contains 10-18 carbon atoms.

The anionic surfactants preferably comprise 2-25% of the liquid phase, more preferably 6-20%.

To achieve the desired paste viscosity, the compositions of the invention preferably contain a sufficient amount of an acid-stable thickener. Thickening silica and thickening clays are well known in the art and are very suitable for this purpose. Suitable thickening clays belong to the group of smectite-type clay minerals, of which bentonite or montmorillonite-type clays are preferred. These materials are preferably used in an amount of 1-25%, more preferably at least 2% or even 5%, based on the liquid phase. Generally, a maximum amount of 15% or even 10%, based on the liquid phase, is sufficient to achieve the desired paste-like properties. Compositions containing a small amount of abrasive material preferably contain a sufficient amount of thickening silica or clay such that the total amount of insoluble solids is at least 35% of the total composition.

The compositions of the invention may contain other known components which are commonly added to cleaning compositions. Thus, they may contain additional surfactants, in particular nonionic and amphoteric surfactants known in the art, provided that they do not interfere with the fluid structuring properties of the anionic surfactant or surfactants present. Suitable surfactants are described in known technical books: "Surface Active Agents" Vol. 1, Schwartz & Perry, Interscience 1949; "Surface Active Agents" Vol. 2, Schwartz, Perry & Berch, Interscience 1958; McCutheon's Emulsifiers and Detergents, current edition, published by the Manufacturing Confectioners Company; Tenside-Taschenbuch, H. Stache, 2nd edition, Carl Hauser Verlag, 1981. However, in general, such nonionic and/or amphoteric surfactants do not contribute significantly to the composition of the invention, but they do represent an additional cost. Therefore, preferably only one of the nonionic or amphoteric surfactants is present, more preferably neither.

Generally, zwitterionic or cationic surfactants do not provide any useful properties, and thus, preferred embodiments of the compositions of the present invention do not include these surfactants.

The compositions of the invention may contain organic solvents to enhance the cleaning effect of the composition. Suitable solvents include, for example, _C1-4 aliphatic alcohols and mono- or diethylene or propylene glycols or their monoethers with C1-6 aliphatic alcohols.

Additional components may be present in the compositions, including perfumes, dyes, optical brighteners, antimicrobials/bactericides, bleaching agents (especially peroxide-type bleaching agents), etc. Additional hydrophobic additives — such as mineral oils, silicone oils or long-chain fatty alcohols — do not provide any beneficial properties in the compositions according to the invention, and silicone oils in particular are preferably omitted.

The compositions of the invention are preferably packaged in containers such as jars or tins from which appropriate amounts can be applied to a suitable device such as a damp cloth or rag, or a container from which the compositions can be dispensed by squeezing, such as a tube. Containers from which the compositions can only be dispensed by pouring are less suitable due to the difficult-to-flow characteristics of the compositions. The compositions of the invention have excellent cleaning properties against a wide variety of soils and stains, but are particularly effective against soils and stains that occur on surfaces in bathrooms and restrooms, such as soap scum, limescale and rust. The compositions are versatile and easier to administer than powder compositions. They have a more concentrated cleaning effect on stubborn dirt than liquid scouring products, and excess product can be easily removed and reused by returning it to the container or container. Similarly, when used against rust or limescale stains by leaving them to dissolve, the products have a stronger cleaning effect than liquid scouring products due to better adhesion and thus increased contact time.

Therefore, the invention also provides a method for removing rust and limescale stains from hard surfaces, comprising the steps of applying the composition of the invention to the stain, allowing the composition to remain on the stain for a sufficient time to completely or partially remove the stain by dissolution, optionally removing the residue of the stain by mechanical rubbing, and removing the composition by wiping and/or rinsing.

The compositions of the present invention may be prepared by methods known in the art, i.e. by mixing the ingredients in the appropriate order. If a thickening silica or clay is used, it is preferred to add these first to the acid and water mixture and allow sufficient time for the material to hydrate before the abrasive is added with mixing. Preferably, the anionic surfactant is added as the last component. The paste structure develops after the addition of the anionic surfactant and takes between 1 and 3 days to fully develop.

In contrast to many prior art solutions, it is not necessary to first prepare a premix of the abrasive and the surfactant in a medium which must then be made alkaline by the separate addition of alkali. The disadvantage of the known solutions lies in the fact that additional acid must be added in order to reduce the pH to the desired value of 3 or below, preferably 2.5 or below, more preferably 2.0 or below. Although several components of the compositions may have a slightly alkaline effect per se, with particular reference to anionic surfactant salts, the compositions according to the invention preferably do not contain any separately added alkali in significant amounts, preferably less than 2%, more preferably 1%, even more preferably less than 0.5% and may be absent. This does not preclude the addition of alkali to neutralize the anionic surfactant acid.

Examples

We prepared acidic abrasive cleaning pastes with the following composition (all % values refer to the total weight of the preparation).

Components Example 1 Example 2 Example 3 Abrasive material: FK45 feldspar 60% 60% 60% Thickening clay: MPV200 3% 4% 3% Anionic surfactant: LAS* 4% 7.4% - Anionic surfactant: SAS** - - 8% Sulfuric acid 2.5% 3% 2.5% Perfume 0.2% 0.2% 0.2% Water Up to 100%

*) Isorchem 113™.

**) Hostapur SAS 60™.

Figure 1 shows the viscosity of the compositions according to the above example as a function of shear stress.

Claims (11)

PATENT CLAIMS 1. An aqueous-based acidic cleaning composition comprising an acid, an abrasive and an anionic surfactant, characterized in that the anionic surfactant is capable of forming a structured liquid with a dilute acid; the preparation contains an inorganic acid; the pH of the composition is between 0 and 2; the preparation is a paste with a plateau viscosity of more than 1000 Pa at a shear stress of 10 Pa and a viscosity of less than 0.1 Pa at a shear stress of 100 Pa 2. The composition of claim 1, wherein the inorganic acid is selected from sulfuric acid and sulfamic acid. 3. The composition of claim 1 or 2, further comprising a di- or polycarboxylic acid. 4. The composition according to any one of claims 1-3, having a pH of 1 or below. 5. A composition according to any one of claims 1-4, comprising 20-75% of a mineral abrasive having a Mohs hardness of 1-7 and a weight average particle size of 0.5-500 µm. 6. A composition according to any one of claims 1-5, wherein the anionic surfactant is selected from alkylbenzene sulfonates and secondary alkane sulfonates, and is present in an amount of between 2 and 25% based on the liquid phase. 7. Compositions according to claims 1-6, which contain an acid-stable thickener. 8. The composition of claim 7, wherein the acid-stable thickening agent is selected from thickening silica and thickening clays, and is used in an amount of 1-25% based on the liquid phase. 9. Compositions according to claims 1-8, which do not contain a zwitterionic or cationic surfactant. 10. Compositions according to claims 1-9, which do not contain a nonionic or amphoteric surfactant. 11. A method for removing rust and limescale stains from hard surfaces, characterized in that the operation comprises the steps of applying the composition of the invention to the stain, allowing the composition to stand on the stain for a sufficient time to completely or partially remove the stain by dissolution, and optionally removing the residue of the stain by mechanical means. 5 by rubbing, and removing the composition by wiping and/or rinsing. The authorized person: Patent and Trademark Office Ltd. Dr. Ferenc Török, patent attorney ORIGINAL PATENT CLAIMS 1. An aqueous-based acidic cleaning composition comprising an acid, an abrasive and an anionic surfactant, characterized in that the anionic surfactant is capable of forming a structured liquid with a dilute acid; the pH of the composition is between 0 and 3; the composition is a paste having a plateau viscosity of greater than 1000 Pa at a shear stress of 10 Pa and a viscosity of less than 0.1 Pa at a shear stress of 100 Pa. 2. The composition of claim 1, which comprises an inorganic acid. 3. The composition of claim 2, wherein the inorganic acid is selected from sulfuric acid and sulfamic acid. 4. The composition according to any one of claims 1-3, further comprising a di- or polycarboxylic acid. 5. A composition according to any one of claims 1-4, comprising 20-75% of a mineral abrasive having a Mohs hardness of 1-7 and a weight average particle size of 0.5-500 µm. 6. A composition according to any one of claims 1-5, wherein the anionic surfactant is selected from alkylbenzene sulfonates and secondary alkane sulfonates, and is present in an amount of between 2 and 25% based on the liquid phase. 7. Compositions according to claims 1-6, which contain an acid-stable thickener. 8. The composition of claim 7, wherein the acid-stable thickening agent is selected from thickening silica and thickening clays, and is used in an amount of 1-25% based on the liquid phase. 9. A method for removing rust and limescale stains from hard surfaces, characterized in that the operation comprises the steps of applying the composition of the invention to the stain, allowing the composition to remain on the stain for a sufficient time to completely or partially remove the stain by dissolution, optionally removing the residue of the stain by mechanical rubbing, and removing the composition by wiping and/or rinsing. totl# i / οέ-χχ λότ.^ι. r