DE68922522T2 - Acidic cleaner for hard surfaces. - Google Patents

Description

This invention relates to a cleaner for hard surfaces such as bathtubs, sinks, tiles, porcelain and enamelware which removes soap scum, limescale and greasy dirt from such surfaces without damaging them. In particular, the invention relates to an acidic microemulsion which can be sprayed onto the surface to be cleaned and wiped off without the usual rinsing and yet leaves the cleaned surface clear and shiny. The invention also relates to a method of using such compositions.

Hard surface cleaners such as bathroom cleaners and scouring cleaners have been around for many years. Scouring cleaners typically include a soap, a synthetic organic detergent or surfactant, and an abrasive. Such products can scratch relatively soft surfaces and may contribute to their dull appearance. They are also often ineffective in removing limescale (usually encrusted calcium and magnesium carbonates) under normal use. Because limescale can be removed by chemical reactions with acidic media, various acidic cleaners have been manufactured and have been used with varying degrees of success. In some cases, such cleaners have failed because the acid used was too strong and damaged the surfaces being cleaned. Other times, the acidic component of the cleaner reacted objectionably with other components of the product, adversely affecting, for example, the cleaning agent or perfume. Some cleaners required subsequent rinsing to avoid leaving objectionable deposits on the cleaned surfaces. As a result of research carried out to overcome the above-mentioned disadvantages, an improved liquid cleaning composition in the form of a stable microemulsion has recently been prepared, which is an effective cleaner in removing soap scum, lime scale and greasy soiling from hard surfaces such as bathtub surfaces and after Application does not require rinsing. One such product is described in U.S. Patent No. 5,076,954 for Stable Microemulsion Cleaning Compositions, filed November 12, 1987 by Loth, Blanvalet and Valange, which application is incorporated herein by reference. In particular, Example 3 of that application discloses an acidic, clear, oil-in-water microemulsion which is stated to have been successfully used to clean shower pan tiles of lime scale and soap scum adhered thereto. Such cleaning was accomplished by applying the cleaner to the walls, then wiping or minimally rinsing, and allowing the walls to dry to give a good shine.

The described microemulsion cleaner of the patent application is effective in removing limescale and soap scum from hard surfaces and is easy to use, but it has been found that its mixture of acidic agents (succinic, glutaric and adipic acids) can damage the surface of some hard objects such as those of materials which are not acid resistant. One such material is an enamel which has been widely used in Europe as a coating for bathtubs and is referred to herein as European enamel. It has been described as zirconium white enamel or zirconium white powder enamel and has the advantage of being resistant to cleaning agents, making it suitable for use on tubs, sinks, shower tiles and bathroom enamelware. Such enamel, however, is sensitive to acids and it is significantly damaged by use of the acidic microemulsion cleaner based on the three organic carboxylic acids previously mentioned. This problem has been solved by the present invention, according to which additional acidic materials are incorporated into the cleaner together with the organic acids, and instead of aggravating the problem, they prevent damage to such European enamel by these organic acids. A mixture of such additional acids, phosphonic and phosphoric acids, also surprisingly improves the safety of the aqueous cleaner for use on such European enamel surfaces and reduces the price of the cleaner. The present invention therefore allows the cleaning of European enamel surfaces as well as other acid-resistant surfaces of bathtubs and other bathroom surfaces by the invented emulsion. However, the product should not be used on various other materials that are particularly sensitive to the attack of acidic media, such as marble.

According to the invention, an acidic, aqueous cleaner for bathtubs and other objects with hard surfaces that are acid-resistant or made of zirconium white enamel, the cleaner having a pH in the range of 1 to 4 and removing limescale, soap scum and greasy dirt from surfaces of such objects without damaging these surfaces, comprises: a cleaning portion of synthetic organic cleaning agent capable of removing greasy dirt from such surfaces, a limescale and soap scum removing portion of dicarboxylic acid(s) having 2 to 10 carbon atoms therein, aminoalkylenephosphonic acid in such a proportion that damage to zirconium white enamel surfaces of objects to be cleaned by the dicarboxylic acid(s) is prevented when the cleaner is used to clean such surfaces, and an aqueous medium for the cleaning agent, the dicarboxylic acid(s) and the aminoalkylenephosphonic acid.

In the present compositions, the synthetic organic detergent may be any suitable anionic, nonionic, amphoteric, ampholytic, zwitterionic or cationic detergent or a mixture thereof, but the anionic and nonionic detergents are preferred as are mixtures thereof. Of the anionic The more preferred solubilizing cations for detergents are the water-soluble salts of lipophilic sulfonic and sulfuric acids, the lipophilic moieties of which contain long chain aliphatic groups, preferably long chain alkyl groups, having from 8 to 20 carbon atoms, more preferably from 12 to 18 carbon atoms. Although several different types of solubilizing cations may be present in the detergents, it is usually preferred that they be alkali metal, e.g. sodium or potassium or a mixture thereof, ammonium or lower alkanolamine having 2 or 3 carbon atoms per alkanol moiety. It is a desirable feature of the present invention that sodium can be the alkali metal used and the resulting emulsion is stable and effective.

Highly preferred salts of lipophilic sulfonic acids are paraffin sulfonates, in which the paraffin group has 12 to 18 carbon atoms, preferably 14 to 17 carbon atoms. Other useful sulfonates are olefin sulfonates, in which the olefin starting material has 12 to 18 carbon atoms, e.g. 12 to 15 carbon atoms, and linear alkylbenzene sulfonates, in which the alkyl group has 12 to 18 carbon atoms, preferably 12 to 16 carbon atoms, e.g. 12 or 13. All of these sulfonates are preferably used in the form of their sodium salts, but other salts are also useful.

Highly preferred salts of lipophilic sulfuric acids are those of higher alkyl ethoxylate sulfuric acids, which may also be referred to as higher alkyl ethyl ether sulfuric acids. The higher alkyl groups of such compounds have the chain lengths given above for this class of anionic detergents, 10 to 18 carbon atoms, and preferably have 10 to 14 carbon atoms, e.g. 12 or about 12 carbon atoms. Such compounds should contain 1 to 10 ethylene oxide groups per mole, preferably 3 to 7 ethylene oxide groups per mole, e.g. 5. A preferred cation is Sodium, but the cations mentioned above for solubilization functions may be used under appropriate circumstances.

The nonionic detergents useful in the present invention can be any of the known nonionic detergents (as can the anionic detergents that meet the requirements set forth in this specification). Many such detergents have been described in the article Surface Active Agents (Their Chemistry and Technology) by Schwartz and Perry and in various annual issues of John W. McCutcheon's Detergents and Emulsifiers. However, they are usually condensation products of a lipophilic moiety such as a higher alcohol or phenol or a propylene glycol or propylene oxide polymer with ethylene oxide or ethylene glycol. In some of the condensation products of ethylene oxide and higher fatty alcohol or alkyl substituted phenol (the alkyl group on the phenol nucleus usually having 7 to 12 carbon atoms, preferably 9 carbon atoms), some propylene oxide may be mixed with the ethylene oxide so that the lower alkylene oxide content is mixed in the nonionic detergent, whereby the hydrophilic-lipophilic balance (HLB) can be controlled.

Highly preferred nonionic cleaning agents present in the compositions of the invention are condensation products of a fatty alcohol having 8 to 20 carbon atoms and 3 to 20 moles of ethylene oxide, preferably of a linear alcohol having 9 to 15 carbon atoms, such as 9 to 11 or 11 to 13 carbon atoms or an average of about 10 to 12 carbon atoms, and 3 to 15 moles of ethylene oxide, such as 3 to 7 or 5 to 9 moles of ethylene oxide, eg about 5 or 7 moles thereof. Instead of the higher fatty alcohol, one can use an alkylphenol such as one having 8 to 10 carbon atoms in a linear alkyl group, eg nonylphenol, and the phenol can be condensed with 3 to 20 ethylene oxide groups, preferably 8 to 15 ethylene oxide groups. condensed. Similarly functioning nonionic detergents which are polymers of mixed ethylene oxide and propylene oxide may be used at least in part in place of the other nonionic detergents. Among such are those sold under the trademark Plurafac such as Plurafac RA-30 and Plurafac LF-400 and available from BASF. Preferred of such nonionic detergents contain 3 to 10 ethoxy groups, preferably about 7, and 2 to 7 propoxy groups, more preferably about 4, and are condensed with a higher fatty alcohol having 12 to 16, more preferably 13 to 15 carbon atoms to form 1 mole of nonionic detergent.

The various non-ionic cleaning agents and the anionic cleaning agents are often mixtures which fall within the individual specifications given herein.

The active acid component of the emulsions is a carboxylic diacid (dicarboxylic acid) which is strong enough to lower the pH of the emulsion to one in the range of about 1 to 4. Various such dicarboxylic acids have been found to be effective and best at removing soap scum and lime scale from bathroom surfaces, while still not destabilizing the emulsion. Of the group of dicarboxylic acids, which includes those having 2 to 10 carbon atoms, from oxalic acid to sebacic acid, suberic, azelaic and sebacic acids are of lower solubilities and therefore not as useful in the emulsions of the invention as the other dibasic aliphatic fatty acids, all of which are preferably saturated and straight chain. Oxalic and malonic acids, although also useful as reducing agents, may be too strong for gentle cleaning of hard surfaces. Preferably, such dibasic acids are those from the middle range of the 2 to 10 carbon atom acid range, especially the 3 to 8 carbon atom range, succinic, glutaric, adipic and pimelic acids, especially the first three of these, which fortunately, are commercially available, in admixture. The diacids, after being introduced into the emulsion of the invention, can be partially neutralized in order to establish the desired pH in the emulsion and to obtain the greatest functional effectiveness with safety.

Phosphoric acid is one of the additional acids that helps protect acid-sensitive surfaces to be cleaned with the present emulsion cleaner. Because it is a tribasic acid, it can also be partially neutralized to obtain an emulsion pH in the desired range. For example, it can be partially neutralized to the bisphosphate, e.g. NaH₂PO₄ or NH₄H₂PO₄.

Aminoalkylenephosphonic acid, the other of the two additional acids for protecting acid-sensitive surfaces from the dissolving action of the dicarboxylic acids of the present emulsions, apparently exists only theoretically, but its derivatives are stable and useful in the invention. These are considered to be aminoalkylenephosphonic acids as this term is used in this description. The aminoalkylenephosphonic acids correspond to the structure

in which Y is an alkylamino or an N-substituted alkylamino group. For example, a preferred aminoalkylenephosphonic acid component of the present emulsions is aminotris(methylenephosphonic acid) which corresponds to the formula N(CH₂PH₂O₃)₃. Other useful aminoalkylenephosphonic acids include ethylenediaminetetra(methylenephosphonic acid), hexamethylenediaminetetra(methylenephosphonic acid) and diethylenetriaminepenta(methylenephosphonic acid). Such aminoalkylenephosphonic acids contain 1 to 3 amino nitrogen atoms, 3 to 5 lower alkylenephosphonic acid groups, in which the lower alkylene group has 1 or 2 carbon atoms, and 0 to 2 alkylene groups each having 2 to 6 carbon atoms, the alkylene(s) being present and linking amino nitrogen atoms when a plurality of such amino nitrogen atoms are present in the aminoalkylenephosphonic acid. It has been found that such aminoalkylenephosphonic acids, which may also be partially neutralized at the desired pH of the microemulsion cleaner, have a desired stabilizing and protective effect in the cleaner according to the invention, particularly when present together with phosphoric acid, and prevent harmful attacks on European enamel surfaces by the diacid component(s) of the cleaner. Typically, the salts of the phosphorus-containing acids, if present, are monosalts of each of the phosphorus and/or aminoalkylenephosphonic acid groups present.

The water used in the preparation of the present microemulsions may be tap water, but it is preferably of low hardness, normally having a hardness, as calcium carbonate, of less than 150 parts per million (ppm). Useful cleaners can also be prepared with tap water having a hardness higher than CaCO3 and up to 300 ppm. Most preferably, the water used is distilled or deionized water in which the content of hardness ions is less than 25 ppm, usually 0. The use of such deionized water allows the preparation of a product with correspondingly good qualities, regardless of hardness variations in the aqueous medium.

Various other components may be present in the cleaners of the invention, including preservatives, antioxidants or corrosion inhibitors, co-solvents, co-surfactants, polyvalent metal ions, perfumes, colorants and terpenes (and terpineols), but various other adjuvants conventionally used in liquid cleaners and hard surface cleaners may also be present provided that they do not interfere with the cleaning, foaming and crust removal functions of the cleaner. Of the various adjuvants (so named because they are not necessarily required to produce a functioning cleaner, although they may be very desirable components of the cleaner), the most important are considered to be the perfumes, which with terpenes, terpineols and hydrocarbons (which may be used in place of or added to the perfumes) act as specially effective solvents for greasy soils on hard surfaces to be cleaned and form the dispersed phases of oil-in-water (O/W) microemulsions. Also of functional importance are the co-solvent and polyvalent metal ions, the former helping to stabilize the microemulsion and the latter helping to improve the cleaning action, particularly with more dilute cleaners and when the polyvalent salts of the anionic detergent used are more effective detergents against greasy soils encountered during use.

The various perfumes which have been found useful in forming the dispersed phase of the O/W microemulsion cleaners may be those normally used in cleaning products and preferably normally in the liquid state. They include esters, ethers, aldehydes, alcohols and alkanes used in perfumery, but of greatest importance are the essential oils which have a high terpene content. It appears that the terpenes (and terpineols) act in conjunction with the cleansing components of the microemulsions to improve the cleansing action of the compositions of the invention, in addition to forming the stable dispersed phase of the microemulsions. According to the invention it has been found that, particularly when pine perfume is used, one can reduce the level of comparatively expensive perfume and replace it with α-terpineol. and in some cases with other terpenes. For example, for every 1% of perfume, 60 to 90% of it, eg about 80%, can be replaced with α-terpineol and essentially the same pine scent is obtained with good cleaning effect and microemulsion stability. Terpenes and other terpene-like compounds and derivatives can be used in a similar way, but α-terpineol is considered to be the best.

The multivalent metal ions present in the cleaners of the invention may be any suitable ions including magnesium (usually preferred), aluminium, copper, nickel, iron or calcium and the ions or mixtures thereof may be added in a suitable form, sometimes as an oxide or hydroxide but usually as a water soluble salt. It appears that the multivalent metal ion reacts with the anion of the anionic detergent (or replaces the detergent cation or produces an equivalent solution in the emulsion) improving the cleaning action and generally also improving other properties of the product. If the multivalent metal ion reacts with the detergent anion to form an insoluble product, such a multivalent ion should be avoided. For example, calcium reacts with the paraffin sulphonate anion to form an insoluble salt so calcium ions obtained from, for example, calcium chloride are omitted from emulsion cleaners containing paraffin sulphonate detergents. Similarly, those polyvalent ions or other components of the compositions of the invention which adversely react with other components are also omitted. As previously mentioned, the polyvalent metal ion is preferably magnesium and it is added to the other emulsion components in the form of a water-soluble salt. A preferred of such salts is magnesium sulfate, which is usually used in the form of its heptahydrate (Epsom salts), but other hydrates thereof or the anhydride may also be used. The sulfates of polyvalent metals are generally used because the sulfate anion thereof is also the anion of some of the anionic detergents and is found in some of such detergents as a by-product of neutralization.

The co-surfactant component(s) of the microemulsion cleaners reduce the interfacial tension or surface tension between the lipophilic droplets and the continuous aqueous medium to a value often close to 10-6 N/m (10-3 dynes/cm), causing the dispersed phase droplets to spontaneously break down until they become small enough to be visible to the human eye, forming a clear microemulsion. In such a microemulsion, the surface area of the dispersed phase is significantly increased and its solvency and grease removal ability are also increased, making the microemulsion significantly more effective as a cleaner for removing greasy soils than if the dispersed phase beads were of a typical emulsion size. The cosurfactants useful in the cleaners of the present invention are: water-soluble lower alkanols having 2 to 4 carbon atoms per molecule (sometimes preferably 3 or 4), polypropylene glycols having 2 to 18 propoxy units, monoalkyl lower glycol ethers of the formula RO(X)nH, in which R is C1-4 alkyl, X is CH2CH2O, CH2CH2CH2O, or CH(CH3)CH2O, and n is 1 to 4, monoalkyl esters of the formula R1O/X)nH, in which R1 is C2-4 acyl and X and n are as described immediately above, aryl substituted alkanols having 1 to 4 carbon atoms, Propylene carbonate, aliphatic mono-, di- and tricarboxylic acids with 3 to 6 carbon atoms, mono-, di- and trihydroxy-substituted aliphatic mono-, di- and tricarboxylic acids with 3 to 6 carbon atoms, higher alkyl ether polylower alkoxycarboxylic acids, lower alkyl mono-, di- and triesters of phosphoric acid, where the lower alkyl group has 1 to 4 carbon atoms, and mixtures thereof.

Examples of such co-surfactants are succinic, glutaric and adipic acids, diethylene glycol monobutyl ether, dipropylene glycol monobutyl ether and diethylene glycol monoisobutyl ether, which are considered to be the most effective.

From the foregoing description of co-surfactants useful in the present cleaners, it appears that succinic, glutaric and adipic acids and a mixture of such components are useful in lowering the pH of the product so that it readily removes soap scum and lime scale from surfaces to be cleaned, and at the same time they act as co-surfactants, improving the appearance of the product and making it more effective in removing grease from such surfaces. Similar dual effects can be obtained using other of the specified acidic materials which have co-surfactant activities in the described cleaners.

Although it is preferred that the present cleaning compositions be in the form of aqueous microemulsions, it is within the scope of the invention to use less preferred emulsions (where the dispersed phase beads are larger), but in such cases the cleaning power of the product is lower because there is not as good contact of the cleaner with the surface being treated. Although microemulsions are the preferred embodiments of the invention, other emulsions and other forms of composition may also be used, such as gels, pastes, solutions, foams and "aerosols" containing aqueous media.

In the cleaners according to the invention, it is important that the proportions of the components are in certain ranges so that the product is most effective in removing greasy dirt, limescale and soap scum and other deposits from the hard surfaces undergoing treatment and in order to protect the surfaces during such treatment. As previously stated, the cleaning agent should be present in a detergent proportion sufficient to remove greasy and oily soils; the proportion of dicarboxylic acid(s) should be sufficient to remove soap scum and lime scale; the aminoalkylenephosphonic acid or phosphoric and aminoalkylenephosphonic acid mixture should be sufficient to prevent damage to acid-sensitive surfaces by the dicarboxylic acid(s); and the aqueous medium should be a solvent and suspending medium for the required components and for any auxiliary agents that may also be present. Normally, such percentages of components are 2 to 8% of synthetic, anionic, organic detergent(s), 1 to 6% of synthetic, organic, nonionic detergent(s), 2 to 10% of aliphatic dicarboxylic acids, 0.05 to 5%, preferably 0.05 to 1% of phosphoric acid or a monosalt thereof, and 0.005 to 2%, preferably 0.01 to 0.2% of aminoalkylenephosphonic acid(s) or aminoalkylenephosphonic monosalt(s) thereof, and the balance water and auxiliaries, if any. Of the dicarboxylic acids, it is preferred that a mixture of succinic, glutaric and adipic acids be used and the ratio thereof is most preferably in the range of 1-3:1-6:1-2, with 1:1:1 and about 2:5:1 ratios being most preferred. The ratios of aminoalkylenephosphonic acid to phosphoric acid to aliphatic dicarboxylic acids are usually about 1:1-20:20-500, preferably they are 1:2-10:10-200 and more preferably they are about 1:4:25, 1:7:170 and 1:3:25, in three exemplary formulations. However, one can have ranges as wide as 1 : 1 - 2000 : 10 - 4000 and sometimes the preferred range of dicarboxylic acid : aminoalkylenephosphonic acid is 5 : 1 to 250 : 1. Similarly, a mixture of succinic, glutaric and adipic acids can have a ratio of 0.8 - 4 : 0.8 - 10 : 1 and the ratio of dicarboxylic acid to phosphoric acid can be 5:2 to 25:1.

Typically present in the cleaner, particularly when paraffin sulfonate is the cleaning agent, is from 0.05 to 5% and preferably from 0.1 to 0.3% of polyvalent ion, preferably magnesium or aluminum, and more preferably magnesium. The percentage of perfume is also normally in the range of from 0.2 to 2%, preferably in the range of from 0.5 to 1.5%, of which at least 0.1% is terpene or terpineol. The terpineol is α-terpineol and is preferably added to allow a reduction in the amount of perfume, the total perfume (including the α-terpineol) consisting of from 50 to 90% terpineol, preferably about 80% thereof.

In preferred formulations of the present cleaners, which differ in that one contains two anionic detergents and the other only one, the latter has a pH in the range of 2.5 to 3.5 and contains 3 to 5% sodium paraffin sulfonate, the paraffin being C₁₄₋₁₇. 2 to 4% non-ionic detergent which is a condensation product of a fatty alcohol having 9 to 15 carbon atoms and with 3 to 15 moles of ethylene oxide per mole of higher fatty alcohol, 3 to 7% of a 1:1:1 or 2:5:1 mixture of succinic, glutaric and adipic acids, 0.1 to 0.3% phosphoric acid, 0.03 to 0.1% aminotris(methylenephosphonic acid), 0.1 to 0.2% magnesium ions, 0.5 to 2% perfume, of which 50 to 90% is α-terpineol, 0 to 5% excipients and 75 to 90% water. More preferably, such cleaners comprise or consist essentially of 4% sodium paraffin (C14-17) sulfonate, 3% of the nonionic detergent, 5% of a 2:5:1 mixture of the dicarboxylic acids, 0.2% phosphoric acid, 0.05% aminotris(methylenephosphonic acid), 1% perfume preferably containing 0.8% α-terpineol, 0.7% magnesium sulfate (anhydrous), 3% excipients and 83% water, alternatively 1% excipients and 81% water.

The other preferred formulation comprises 0.5 to 2% sodium paraffin sulfonate, wherein the paraffin is C₁₄₋₁₇ 2 to 4% sodium ethoxylated higher fatty alcohol sulfate, wherein the higher fatty alcohol contains 10 to 14 carbon atoms and it contains 1 to 3 ethylene oxide groups per mole, 2 to 4% non-ionic detergent which is a condensation product of a fatty alcohol having 9 to 15 carbon atoms and having 3 to 15 moles ethylene oxide per mole of fatty alcohol, 3 to 7% of a 1:1:1 mixture of succinic, glutaric and adipic acids, 0.1 to 0.3% phosphoric acid, 0.01 to 0.05% aminotris(methylenephosphonic acid), 0.09 to 0.17% magnesium ions, 0.5 to 2% perfume, of which at least 10% is terpene(s) and/or terpineol, 0 to 5 % additives and 75 to 90 % water. More preferably, such a cleaner comprising two anionic detergents comprises or consists essentially of 1% sodium paraffinic C14-17 sulfonate, 3% sodium ethoxylated higher fatty alcohol sulfate, wherein the higher fatty alcohol is lauryl alcohol and the degree of ethoxylation is 2 moles of ethylene oxide per mole, 3% nonionic detergent which is a condensation product of a linear C9-11 alcohol and 5 moles of ethylene oxide, 5% of a 1:1:1 mixture of succinic, glutaric and adipic acids, 0.2% phosphoric acid, 0.03% aminotris (methylenephosphonic acid), 0.7% magnesium sulfate (anhydrous), 2% auxiliary and 84% water, alternatively 1% auxiliary and 85% water.

The pH of the various preferred microemulsion cleaners is usually 1 to 4, preferably 1.5 to 3.5, e.g. 3. The water content of the microemulsions is usually in the range of 75 to 90%, preferably 80 to 85%, and the excipient content is in the range of 0 to 5%, usually 1 to 3%. If the pH is not in the desired range, it is usually adjusted with either sodium hydroxide or suitable acid solutions, e.g. sulphuric acid, but normally the pH is raised rather than lowered, and if it needs to be lowered, more of the dicarboxylic acid mixture can be used instead.

The microemulsion cleaners of the invention are clear O/W emulsions and exhibit stability at room temperature as well as at elevated and reduced temperatures of 10 to 50 ºC. They are easily pourable and exhibit a viscosity in the range of 0.002 to 0.15 or 0.2 Ns/m² (2 to 150 or 200 centipoise), e.g. 0.005 to 0.04 Ns/m² (5 to 40 centipoise), as desired, the viscosity being partially controllable by adding a thickener to the formulation, such as lower alkylcelluloses, e.g. methylcellulose, hydroxypropylmethylcellulose, or water-soluble resin, e.g. polyacrylamide, polyvinyl alcohol. Any tendency of the product to foam objectionably can be counteracted by introducing into the formulation free fatty acid or soap in small proportions, as is well known in the detergent art (at low pH the soap converts into acid).

The liquid cleaners can be prepared by merely mixing the various components thereof, the order of additions not being critical. However, with the various water-soluble components to be mixed together, it is desirable to mix the oil-soluble components to be mixed together in a separate operation and to mix the two mixtures, adding the oil-soluble portion to the water-soluble portion (in the water) with stirring or other agitation. In some cases, this procedure can be varied to prevent any undesirable reactions between components. For example, concentrated phosphoric acid is not added directly to magnesium sulfate or to a dye, but such additives are aqueous solutions, preferably dilute aqueous solutions of the components.

The cleaner may desirably be packaged in manually operated spray dispensing containers, usually and preferably made of synthetic, organic, polymeric plastic material such as polyethylene, polypropylene or polyvinyl chloride (PVC). Such containers preferably also comprise a nylon or other non-reactive plastic lid, spray nozzle, dip tube and associated dispensing parts, and the resulting packaged cleaner is ideally suited for use in "spray and wipe" applications. In some cases, such as when lime scale and soap scum deposits are stubborn, the cleaner can be left on until it has dissolved or lifted the deposits and then wiped or rinsed off, or multiple applications can be made followed by multiple removals until the deposits have disappeared. In spray applications, the viscosity of the microemulsion (or ordinary emulsion if used instead) is desirably increased so that the liquid adheres to the surface to be cleaned, which is particularly important when the surface is vertical to prevent immediate runoff of the cleaner and consequent loss of effectiveness. Sometimes the product may be formulated as an 'aerosol spray type' so that its foam delivered from the aerosol container adheres to the surface to be cleaned. On other occasions the aqueous medium may be such as to result in a gel or paste which is applied to the surface by hand application, preferably with a sponge or cloth, and removed by a combination of rinsing and wiping, preferably with a sponge, after which it may be allowed to dry to a shine, or dried with a cloth. Of course, if practicable, the cleaned surface may be rinsed to remove all traces of acid from it.

The following examples illustrate the invention but do not limit it. Unless otherwise indicated, all parts, proportions and percentages in the examples, specification and claims are by weight and all temperatures are in degrees Celsius. EXAMPLE 1 Component Sodium paraffin sulfonate (C₁₄₋₁₇₇ paraffin) Sodium lauryl ether sulfate (2 moles of ethylene oxide [EtO] per mole) Nonionic C₄₋₁₇ linear alcohol ethoxylate Detergent (5 moles of EtO per mole) Magnesium sulfate heptahydrate (Epsom salts) Succinic acid Glutaric acid Adipic acid Aminotris(methylenephosphonic acid) Phosphoric acid Parfum (contains about 40% terpenes) Colorant (1% aqueous solution of blue dye) Sodium hydroxide (50% aqueous solution; reduce the amount of water by the amount of NaOH solution used) Water (deionized)

The microemulsion cleaner is prepared by dissolving the cleaning agents in the water, then adding the remainder of the water soluble materials to the cleaning solution with stirring, except the perfume and the pH adjusting agent (sodium hydroxide solution). The pH is adjusted to 3.0 and then the perfume is stirred into the aqueous solution, immediately yielding the desired microemulsion which is clear blue and has a viscosity in the range of 0.002 to 0.02 Ns/m2 (2 to 20 cP). If the viscosity is lower, or if it is considered desirable to increase it, about 0.1 to 1% of a suitable rubber or resin, such as sodium carboxymethylcellulose or hydroxypropylmethylcellulose, may be incorporated into the formulation. or polyacrylamide or polyvinyl alcohol or a suitable mixture thereof.

The acid cleaner is packaged in polyethylene squeeze bottles, which are fitted with polypropylene spray nozzles which can be adjusted to the closed, spray and jet positions. In use, the microemulsion is sprayed onto the "bathtub ring" on a bathtub which also includes limescale in addition to soap scum and greasy dirt. The application rate is about 5 ml per 5 m of ring (which is about 3 cm wide). After application and a waiting time of about 2 minutes, the ring is wiped with a sponge and rinsed with water. Greasy dirt, soap scum and even the limescale have been found to be effectively removed. In those cases where the limescale is particularly thick or adherent, a second application may be desirable, but this is not considered the norm.

The tub surface may be rinsed because it is so easy to rinse a bathtub (or shower pan), but such rinsing is not necessary. Sometimes a dry wipe is sufficient, but if it is desirable to remove any acid residue from the surface, it may be sponged with water or wiped with a wet cloth, but in such a case it is not necessary to use more than 10 times the weight of the cleaner applied. In other words, the surface need not be thoroughly showered or rinsed with water and it will still be clean and shiny (assuming it was originally shiny). In other applications of the cleaner, it can be used to clean shower tiles, bathroom floor tiles, kitchen tiles, sinks and enamelware, generally without damaging the surfaces thereof. It will be understood that many such surfaces are acid resistant, but a commercial product must be capable of being used on less resistant surfaces without damage. as on European white enamel (often on a cast iron or sheet steel substrate), often referred to as zirconium white powder enamel. It is a feature of the cleaner described above (and other cleaners according to the invention) that they effectively clean hard surfaces, but they contain ionizable acids and therefore should not be applied to acid-sensitive surfaces. They have been found in this example not to damage European white enamel bathtubs which have been significantly damaged by cleaning with preparations exactly as those of this example except that the phosphonic acid or the phosphonic acid-phosphoric acid mixture has been omitted from them.

The main component of the formulation that protects European enamels is phosphonic acid and in the formulations the amount of this acid has been reduced to below the minimum normally required at a pH of 3. Although 0.5% is normally the minimum when phosphoric acid is present, which is ineffective even at such a pH, the effect of the phosphonic acid is nevertheless increased, allowing a reduction in the amount of expensive phosphonic acid.

In variations of the described formulation, all components are kept the same and in equal proportions except water, phosphonic and phosphoric acids. In experiment la, 0.05% aminotris(methylenephosphonic acid) was used and the phosphoric acid was omitted; in experiment 1b, 0.5% ethylenediaminetetra(methylenephosphonic acid) was used and no phosphoric acid was present; in experiment 1c, 0.5% hexamethylenediaminetetra(methylenephosphonic acid) was used and no phosphoric acid was present; in experiment 1d, 0.4% diethylenetriaminepenta(methylenephosphonic acid) was used and no phosphoric acid was present; and in experiment le, 0.10% diethylenetriaminepenta(methylenephosphonic acid) was used together with 0.60% phosphoric acid. The cleaning powers of formulations 1d and 1e were approximately equivalent, demonstrating that the presence of phosphoric acid, which is essentially ineffective in protecting surfaces against the action of the carboxylic acids present in the formulation, reduces the level of phosphonic acid for protecting surfaces to 1/4 of that previously required. Similar effects are obtainable when phosphoric acid is used in formulations 1b and 1c in approximately the same proportions as in Example 1 and Example 1e.

If excessive foaming occurs when using the cleaner, an anti-foaming agent such as a silicone or coconut fatty acid can be added. Alternatively, coconut diethanolamide can be added to increase foaming. EXAMPLE 2 Component Sodium paraffin sulfonate (C₁₄₋₁₇₇ paraffin) Nonionic detergent (condensation product of 1 mole of C₄₋₁₇ fatty alcohol and 5 moles of EtO) Magnesium sulfate heptahydrate Mixed succinic, glutaric and adipic acids (1:1:1) Aminotris(methylenephosphonic acid) Phosphoric acid Perfume Dye (1% aqueous solution of blue dye) Sodium hydroxide (50% aqueous solution; reduce the amount of water by the amount of NaOH solution used) Water (deionized)

The compositions of this example were prepared in the same manner as those of Example 1 and they were also tested in the same manner with similarly good results. The microemulsions were clear and lighter blue in color and the pH thereof was adjusted to 3.0. The cleaners readily removed soap scum and greasy soil from hard surfaces and dissolved and facilitated the removal of lime scale with minimal rinsing or sponge wiping as reported in Example 1. The presence of the aminotris(methylenephosphonic acid) prevented damage to acid sensitive surfaces by the carboxylic acids and the presence of the phosphoric acid allowed the reduction of the amount of aminotris(methylenephosphonic acid used. For example, in Example 2a, 0.10% of the aminotris(methylenephosphonic acid) was required without the presence of phosphoric acid to protect European enamel from damage by the cleaning composition. Similarly to Example 1b, where the formulation was the same except that the phosphonic and phosphoric acids were replaced by 0.20% phosphonic acid (diethylenetriaminepenta(methylenephosphonic acid)) and 0.6% phosphoric acid, European enamel was not damaged, whereas 0.5% phosphonic acid was required to achieve the same desirable effect without the presence of phosphoric acid. Similar results are obtained when the 0.5% of phosphonic acid is replaced by the same proportion of ethylenediaminetetra(methylenephosphonic acid) or hexamethylenediaminetetra(methylenephosphonic acid), with and without additional phosphoric acid.

It can therefore be seen from this example (and Example 1) that phosphoric acid, which is essentially ineffective in protecting acid-sensitive surfaces from the action of carboxylic acids in the present cleaners, enhances the protective effects of phosphonic acids and does so significantly on European bathtub enamel. EXAMPLE 3 Component Water (deionized) C₁₄₋₁₇₁₇ Sodium paraffin sulfonate (60% active ingredient, Hostapur SAS) * Mixture of glutaric, succinic and adipic acids (manufactured by GAF Corp.) Nonionic detergent (Plurafac RA-30, ethoxypropoxy higher fatty alcohol, manufactured by BASF-Wyandotte) Epsom salts Aminotris(methylenephosphonic acid) Phosphoric acid (85%) Parfum (pine scent type, containing terpenes) Alpha-terpineol (perfume substitute) Formalin (preservative) 2,6-di-tert-butyl-para-cresol (antioxidant) CI acid blue 104 dye * 57.5% glutaric acid, 27% succinic acid and 12% adipic acid

The above formulation was prepared in the same manner as described above and tested in the same manner and found to satisfactorily clean greasy soil from articles having hard acid sensitive surfaces such as cast iron tubs and sinks or sheet steel coated with European enamel and to facilitate the removal of soap scum and lime scale from such surfaces. If the phosphonic and phosphoric acids are omitted from the formulation or if only the phosphonic acid is omitted, the cleaner will attack and dissolve such surfaces. The presence of the phosphonic acid permits a reduction in the amount of phosphonic acid required to inhibit the cleaner so that it will not and this reduction is significant, particularly for economic reasons, but equally functional. The α-terpineol replaces some of the perfume and helps to form the microemulsion without destroying the pleasant smell that the perfume imparts to the product, and such results are obtainable with other piney perfumes. The α-terpineol, like the terpene components of a piney perfume, facilitates the formation of a microemulsion, but the terpineol is even more active because it is essentially 100% terpene compound, whereas the perfumes usually comprise less than 50% terpenes.

EXAMPLE 4

If changes are made in the formulations given above by substituting different anionic and nonionic detergents from the types described herein, by using other polyvalent salts (or omitting them), by using other phosphonic acids with or without phosphoric acid and by varying the proportions of the components by ± 10%, 20% and 30% within the ranges given in the description, useful microemulsion cleaners are obtained which satisfactorily clean hard surfaces and remove soap scum and lime scale from them without damaging them, even if they are made of European enamel. The products preferably contain phosphoric acid which improves the protective effect of the phosphonic acid component, but it is within the scope of the invention to omit the phosphoric acid if this is considered desirable and practicable. The cleaners are preferably in microemulsion form, but if the microemulsion 'breaks' to a conventional emulsion, the product is useful as an effective cleaner, so such emulsions are also within the scope of the invention. It may be preferred to dispense the cleaner from a spray bottle, but it may also be packaged in conventional bottles. It may be in the form of a paste or gel so as to make it more adherent to surfaces to which it is applied, so that it remains there and attacks the scale rather than running off the surface. Furthermore, while mixtures have been mentioned in this specification, even if not specifically described, it should be understood that mention of a single component includes reference to mixtures of such components in the cleaners of the invention.

Claims (13)

1. An acidic, aqueous cleaner for bathtubs and other articles with hard surfaces which are acid-resistant or made of zirconium white enamel, the cleaner having a pH in the range of 1 to 4 and removing limescale, soap scum and greasy dirt from surfaces of such articles without damaging these surfaces, and comprising: a cleaning portion of synthetic organic cleaning agent capable of removing greasy dirt from such surfaces, a limescale and soap scum removing portion of dicarboxylic acid(s) having 2 to 10 carbon atoms therein, an aminoalkylenephosphonic acid in such a proportion that damage to zirconium white enamel surfaces of objects to be cleaned by the dicarboxylic acid(s) is prevented when the cleaner is used to clean such surfaces, and an aqueous medium for the cleaning agent, the dicarboxylic acid(s) and the aminoalkylenephosphonic acid. 2. An acidic aqueous cleaner according to claim 1, wherein the dicarboxylic acid(s) is/are aliphatic and has/have a carbon atom content in the range of 3 to 8, the aminoalkylenephosphonic acid contains 1 to 3 amino nitrogen atoms, 3 to 5 lower alkylenephosphonic acid groups in which the lower alkylene has 1 or 2 carbon atoms, and 0 to 2 alkylene groups each having 2 to 6 carbon atoms, the alkylene(s) being present and linking amino nitrogens when a plurality of such nitrogen atoms are present in the aminoalkylenephosphonic acid. 3. Acidic, aqueous cleaner according to claim 2, which is in the form of a liquid emulsion and in which the ratio of Dicarboxylic acid to aminoalkylenephosphonic acid is in the range of 5:1 to 250:1. 4. Acidic, aqueous emulsion cleaner according to claim 3, in which the synthetic organic cleaning agent is a mixture of anionic and non-ionic cleaning agents, wherein the anionic cleaning agent(s) is/are a water-soluble salt of a lipophilic organic sulfonic acid/water-soluble salts of lipophilic organic sulfonic acids and/or a water-soluble salt of a lipophilic organic sulfuric acid/water-soluble salts of lipophilic organic sulfuric acids, the non-ionic cleaning agent is a condensation product of a lipophilic alcohol or phenol with lower alkylene oxide and the aminoalkylenephosphonic acid is selected from the group consisting of aminotris(methylenephosphonic acid), ethylenediaminetetra(methylenephosphonic acid), hexamethylenediaminetetra(methylenephosphonic acid) and diethylenetriaminepenta(methylenephosphonic acid) and Mixtures thereof. 5. Acidic, aqueous, liquid emulsion cleaner according to claims 3 and 4, in which phosphoric acid is also present, which improves the effect of the aminoalkylenephosphonic acid in protecting zirconium white enamel surfaces of objects to be cleaned against the action of the dicarboxylic acid(s), and in which the proportion of phosphoric acid is in the range of 2:1 to 10:1 with respect to the aminoalkylenephosphonic acid, and the ratio of dicarboxylic acid to phosphoric acid is in the range of 5:2 to 25:1. 6. Acidic liquid emulsion cleaner according to claim 5, which contains 2 to 8% synthetic, organic, anionic cleaning agent(s), 1 to 6% synthetic, organic, nonionic cleaning agent(s), 2 to 10% aliphatic dicarboxylic acid(s), 0.05 to 1% phosphoric acid and 0.01 to 0.2% aminoalkylenephosphonic acid(s). 7. Acidic liquid emulsion cleaner according to claim 6, in which the synthetic, organic, anionic cleaning agent is selected from the group consisting of water-soluble, higher paraffin sulfonates and water-soluble, ethoxylated, higher fatty alcohol sulfates having 1 to 10 ethylene oxide groups per mole and mixtures thereof, the nonionic cleaning agent is a condensation product of a fatty alcohol having 9 to 15 carbon atoms with 3 to 15 moles of lower alkylene oxide per mole of higher fatty alcohol, the aliphatic dicarboxylic acid is a mixture of succinic, glutaric and adipic acids in proportions of 0.8 -4:0.8 - 10:1, the aminoalkylenephosphonic acid is aminotris(methylenephosphonic acid) and in the cleaner 0.05 to 0.5% magnesium and/or aluminum ions and 0.2 to 2 % perfume material containing at least 0.1% terpene and/or terpineol, the cleaner being in the form of a microemulsion. 8. Acidic liquid microemulsion cleaner according to claim 7, having a pH in the range of 2.5 to 3.5 and 3 to 5% sodium paraffin sulfonate, wherein the paraffin is C₁₄₋₁₇- paraffin, 2 to 4% nonionic detergent which is a condensation product of a fatty alcohol having 9 to 15 carbon atoms with 3 to 15 moles of lower alkylene oxide per mole of higher fatty alcohol, 3 to 7% of the mixture of succinic, glutaric and adipic acids, 0.1 to 0.3% phosphoric acid, 0.03 to 0.1% aminotris(methylenephosphonic acid), 0.1 to 0.2% magnesium ions, 0.5 to 2% perfume, of which 50 to 90% α-terpineol, 0 to 5% excipients and 75 to 90% water. 9. Acidic liquid microemulsion cleaner according to claim 8, which contains 4% sodium paraffin sulfonate, 3% nonionic detergent, 5% of a 2:5:1 mixture of succinic, glutaric and adipic acids, 0.2% phosphoric acid, 0.05% aminotris(methylenephosphonic acid), 1% perfume, 0.7% magnesium sulfate, anhydrous, 1% excipients and 81% water. 10. An acidic liquid microemulsion cleaner according to claim 7, comprising 0.5 to 2% sodium paraffin sulfonate, wherein the paraffin is C₁₄₋₁₇ paraffin, 2 to 4% sodium ethoxylated higher fatty alcohol sulfate, wherein the higher fatty alcohol has 10 to 14 carbon atoms and the ethoxylated sulfate contains 1 to 3 ethylene oxide group per mole, 2 to 4% nonionic detergent which is a condensation product of fatty alcohol having 9 to 15 carbon atoms with 3 to 15 moles of ethylene oxide per mole of higher fatty alcohol, 3 to 7% of a 1:1:1 mixture of succinic, glutaric and adipic acids, 0.1 to 0.3% phosphoric acid, 0.01 to 0.05 % Aminotris (methylenephosphonic acid), 0.09 to 0.17 % magnesium ions, 0.5 to 2 % perfume, of which at least 10 % is terpene(s) and/or terpineol, 0 to 5 % excipient(s) and 75 to 90 % water. 11. An acidic liquid microemulsion cleaner according to claim 10, which comprises 1% sodium paraffin sulfonate, 3% sodium ethoxylated higher fatty alcohol sulfate, 3% nonionic detergent, 5% of a 1:1:1 mixture of succinic, glutaric and adipic acids, 0.2% phosphoric acid, 0.03% aminotris(methylenephosphonic acid), 0.7% magnesium sulfate, 1% perfume, 1% excipients and 85% water. 12. A method for removing one or more of limescale, soap scum and greasy dirt from bathtubs or other objects with a hard surface which is resistant to acid or made of zirconium white enamel, which comprises applying to such a surface a composition according to claim 1 and rinsing said composition and the limescale and/or the soap scum and/or greasy dirt are removed from this surface. 13. A method for removing one or more of limescale, soap scum and greasy dirt from bathtubs or other hard surfaced objects which are acid resistant or made of zirconium white enamel, which comprises applying to such a surface a composition according to claim 7 and removing said composition and the limescale and/or soap scum and/or greasy dirt from said surface.