WO1992003528A1

WO1992003528A1 - Hard surface cleaner

Info

Publication number: WO1992003528A1
Application number: PCT/AU1991/000378
Authority: WO
Inventors: Donald Neil Furlong; Calum John Drummond; George Georgaklis; Boris Frank Cvetko
Original assignee: R & C Products Pty. Ltd.; Commonwealth Scientific And Industrial Research Organisation
Priority date: 1990-08-22
Filing date: 1991-08-22
Publication date: 1992-03-05

Abstract

A clear hard surface cleaner which is in the form of a microemulsion is disclosed. The hard surface cleaner comprises a) 1 to 26 wt % of an abrasive with a single value refractive index of not more than 1.477 which is dispersed in said compositions; b) one or more anionic or nonionic surfactants selected from the group consisting of alkyl benzene sulfonates, saturated and unsaturated fatty acid soaps, amine oxides, sarcosinates, alkyl ethoxysulphates, betaines, alcohol ethoxylates, ethoxylated fatty amines, nonyl phenol ethoxylates, sucrose esters, alkyl glucosides and fatty acid alkanolamides, or mixtures thereof; c) sufficient of a component to adjust the refractive index of the continuous phase to that of the abrasive; d) one or more oil and grease solvents selected from the group consisting of hydrocarbons, cineole, terpene alcohols, terpene aldehydes, and terpene ketones, or mixtures thereof, in the dispersed phase; and e) water. Preferred abrasives are silica and polytetrafluorethylene.

Description

HARD SURFACE CLEANER FIELD QF THE INVENTION

This invention relates to hard surface cleaning compositions, in particular to abrasive-based liquid compositions which are clear and especially useful for cleaning oily and greasy soils from substrates. BACKGROUND TO THE INVENTION

Liquid detergent compositions, usually in solution or emulsion form, have been used as all-purpose cleaners for a variety of surfaces including hard surfaces such as bathtubs, tiles, bench tops sinks, painted surfaces, stove tops and the like. The prior art describes many such compositions.

Some of these compositions utilize substantial concentrations of inorganic phosphate builder salts to achieve effective cleaning. The presence of such salts is undesirable both for environmental reasons and the tendency to deposit phosphate on the cleaned surface thereby necessitating additional rinsing. Other compositions, whilst being phosphate-free, frequently utilize higher concentrations of surfactant thereby having a tendency towards excessive foaming.

The aforementioned compositions are generally in emulsion form, although the prior art discloses hard surface cleaners in the form of microemulsions.

Representative of these prior art compositions are those disclosed in European Patent Application Nos. 0137615, 0137616, 016072 and 0316726 and US 4561991. These compositions include detergent, solvent, water and a co-surfactant.

Still other compositions that are useful hard surface cleaners are those which include an abrasive in suspension, generally an aqueous suspension, together with an effective level of surfactant. A typical composition of this type is disclosed in GB 955081 (Unilever Limited) . These prior art compositions may in general terms comprise effective hard surface cleaners. However, the present inventors in seeking to understand the manner in which soil removal from hard surfaces occurs, found that there were a number of characteristics and components that were essential to producing compositions that were effective hard surface cleaners, having acceptable environmental and organoleptic characteristics whilst meeting the cost expectations of consumers. Broadly, it was found that an effective hard surface cleaner, that went some way towards meeting these criteria should be in the form of a microemulsion and include an abrasive, a surfactant, and an oil and grease solvent.

Whilst the prior art discloses hard surface cleaners that are icroemulsions, there is no disclosure or teaching to suggest the inclusion therein of an abrasive or indeed that it is essential. This is understandable when it is realized that one of the important characteristics of a microemulsion is that it appears clear, whereas the inclusion of an abrasive would generally render the composition opaque.

In recognition of not only the aesthetic appeal of a clear hard surface composition but also of the utility of being able to easily observe the extent of removal of soil from the surface, the present inventors believe that desirably a hard surface cleaner composition should be clear. Moreover, the high surface area of the oil and grease solvent due to its presence as microdroplets, is believed to enhance the cleaning efficiency of microemulsion type compositions.

Summary of the Invention Accordingly the present invention consists in a clear hard surface cleaning composition in the form of a microemulsion comprising: (a) 1 to 26 wt% of an abrasive with a single value refractive index of not more than 1.477 which is dispersed in said composition;

(b) one or more anionic or nonionic surfactants selected from the group consisting of alkyl benzene sulfonates, saturated and unsaturated fatty acid soaps, a ine oxides, sarcosinates, alkyl ethoxysulphates, betaines, alcohol ethoxylates, ethoxylated fatty amines, nonyl phenol ethoxylates, sucrose esters, alkyl glucosides and fatty acid alkanolamides, or mixtures thereof;

(c) sufficient of a component to adjust the refractive index of the continuous phase to that of the abrasive;

(d) one or more oil and grease solvents selected from the group consisting of hydrocarbons, cineole, terpene alcohols, terpene aldehydes, and terpene ketones, or mixtures thereof, in the dispersed phase; and

(e) water.

Disclosure of the Invention As used in the specification, the term "clear" as it relates to hard surface cleaners of the invention means having a turbidity of not more than 250 Nephelometric Turbidity Units (NTU) when determined using a HACH Ratio Turbidimeter Model No. 18900 using a 23mm path length. An important limitation on the selection of an abrasive is that it must have a single refractive index that permits the refractive index of the continuous phase to be matched thereto, thus producing a clear composition. Two abrasives that have been found to be suitable are silica and polytetrafluoroethylene having a refractive of about 1.370.

The preferred abrasive is silica owing to the relative ease with which the refractive index of the continuous phase may be matched thereto.

Furthermore, the silica is useful in the composition as it contributes to the viscosity and rheological properties of the composition.

The abrasive will be incorporated in the composition at a concentration of about 1 to 26 wt%. However, as the level of cleaning performance required will to a certain extent relate to the concentration of abrasive, the actual concentration used may be varied widely.

When silica is to be used, with respect to cleaning performance, a concentration of from 8 to 16 wt% is preferred. Particularly preferred is a concentration range of from 10 to 13 wt% as this results in compositions having the desired viscosity and rheological characteristics.

Another relevant factor in selecting an abrasive is its particle size as there is a relationship between particle size and cleaning performance. In the context of the compositions of the invention, when silica is used, the average aggregate size should be in the range of about 0.01 micron to about 75 micron. Preferably, up to 20 microns, most preferably in the range of about 6 to 13 microns.

When polytetrafluoroethylene is used as an abrasive, the average aggregate size will lie in the range of 0.01 micron to 75 micron, preferably about 10-40 micron. Sufficient of a component is included in the compositions of the invention to adjust the refractive index of the continuous phase to that of the abrasive. Whilst a variety of compounds may potentially be used to achieve a satisfactory refractive index, it is important to realize that some of these compounds may be incompatible or result in compositions that are in some way inferior.

As the compositions have an aqueous continuous phase, desirably the refractive index adjusting component will be aqueous based. Thus the choice of compound(s) to provide the appropriate refractive index requires that they be water soluble or miscible and of sufficiently high refractive index to match the abrasive.

As silica has been found to be a preferred abrasive, the present inventors have found a number of compounds which when formed into aqueous solution provide a continuous phase of a refractive index of about 1.45, being that of silica. These compounds are: t-butyl alcohol glycerol sorbitol urea lactose, and sucrose

For reasons of economy and performance, it has been found that a refractive index adjusting component which comprises a solution of sucrose/urea/glycerol/water is particularly useful. Such a component may have sucrose in a concentration of up to about 35 wt%, urea about 25-45 wt%, glycerol about 5-35 wt%, the balance being water. It is, however, possible to achieve a refractive index of up to 1.477, thereby allowing for the use of other high refractive index abrasives. A suitable refractive index adjusting component to achieve a refractive index of 1.477 consists of 31wt% sucrose, 29wt% urea, 25wt% glycerol and 15wt% water.

To stabilize the microemulsion and contribute to effective cleaning, at least one surfactant is included in the hard surface cleaner compositions of the invention. Suitable surfactants may be selected from anionics, nonionics or mixtures thereof. In addition two or more surfactants of the same type may be used.

Anionic surfactants that may be used include alkylbenzene sulfonates such as dodecylbenzene sulfonate, saturated and unsaturated fatty acid soaps exemplified by sodium oleate and sodium laurate, amine oxides such as lauryldimethylamine oxide and cocodimethylamine oxide, sarcosinates such as sodium lauryl sarcosinate, alkyl ethoxysulphates and betaines such as cocoamidopropyldi- methylamine oxide. Nonionic surfactants that may be used include alcohol ethoxylates, particularly linear alcohol ethoxylates, ethoxylated fatty amines, nonyl phenol ethoxylates, sucrose esters, alkyl glucosides and fatty acid alkanolamides. Examples of these surfactants include sucrose oleate, sucrose monolaurate, alkyl dextrose, sodium coco-hydrolysed animal protein, dodecyl ether of maltose, octyl ether of glucose and coconut diethanolamide.

The most preferred surfactants are alkylbenzene sulfonates, fatty acid amines, alkylethoxy sulphates and betaines.

Preferably a mixture of anionic and nonionic surfactant is used. Most preferably a mixture of alkyl benzene sulfonate and either a linear alcohol ethoxylate or a fatty acid diethanolamide. The surfactant content may be varied widely depending at least on the level of cleaning performance required. Other factors that need to be considered in both selecting the surfactant and the concentration to be used is the need to ensure the stability of the microemulsion and the effect on viscosity and cost. However, generally the surfactant content will be in the range of about 1 to 10 wt%, preferably about 3 to 7 wt%.

To provide a satisfactory cleaning performance, particularly in respect of oil and grease type soil removal, an oil and grease solvent is included in the dispersed phase.

A wide range of solvents may be used including hydrocarbons such as cyclohexane, decane and terpenes. Cineole, terpene alcohols, terpene aldehydes and terpene ketones may also be used. In general terms terpenes are preferred for use as the solvent, particularly limonene, cumene and pinene.

The concentration of solvent in the compositions of the invention will usually be no more than about 10 wt%, preferably less than about 5 wt%. Of course it must be realised that generally the higher the concentration of solvent, the more difficult it is to achieve stability of the microemulsion. Furthermore, unless there is a significant improvement in cleaning performance, the increased cost. of compositions containing higher levels of solvent is not warranted.

An important characteristic of the finished product is that it has a satisfactory viscosity/rheological profile. Naturally, the choice of viscosity will to a certain extent be governed by the manner in which the hard surface cleaner is to be dispensed. For example, a cleaner of excessively high viscosity may not be capable of being dispensed from a container where it is required to flow out under gravity. Equally unsatisfactory would be a cleaner that was so thin that it was difficult to prevent dispensing excessive amounts of cleaner.

Viscosity to a certain extent also has an effect on cleaning performance. Thus, generally if the viscosity is too high it will impede cleaning performance. However, a cleaner that is too thin will generally not be useful in cleaning vertical or angular surfaces due to a tendency to run off the surface.

In the cleaning compositions of the present invention, viscosity has been determined at 25 C ± 0.1 C using a Brookfield LVT viscometer fitted with a No. 3 spindle and operated at 60 rpm.

Under these conditions, viscosities in the range of about 500 - 3000 cps were found to be satisfactory. Preferably, in the range 800 - 2000 cps, most preferably around 1500 cps. These viscosity determinations refer to initial viscosity, that is viscosity determined within about 12 hours of preparation of a composition. In some cases, viscosity will increase in time to levels of the order of 10,000 cps.

It is also important to consider the effect that viscosity has on the ability of the cleaner to maintain the abrasive in suspension. Clearly if the viscosity of the cleaner is too low, then abrasive will tend to sediment .out. This will give a cleaner of variable, unsatisfactory performance.

In some compositions of the invention, a strong ionic salt such as sodium chloride may be added to achieve the requisite viscosity. Generally, the amount of salt added will be small, no more than about 0.5 wt%.

Another important characteristic of the cleaner of the invention is its pH. As the cleaner is particularly useful for the removal of oil and grease soils, ideally the cleaner will be alkaline. Generally the pH will be greater than about 9.0, preferably greater than about 10, most preferably 10.5 to 11.5.

However, when the cleaner includes as a nonionic surfactant, sucrose esters, for reasons of stability and cleaning performance, it is preferred that the pH be in the range of from 6.0 to 8.0.

It should be realised that a determining factor in selection of pH will be the nature of the surfactant(s) chosen. Thus, when alkyl benzene sulphonic acid is chosen, it will be preferably neutralised with sodium hydroxide to ensure that it is present in the cleaner as the sodium salt. A cleaner including, for example, sodium dodecylbenzene sulphonate will have a pH of about 10.5.

Although the cleaners of the invention may be prepared using a variety of procedures, one method will now be described. A base aqueous phase consisting of the refractive index adjusting component is prepared. If necessary, the pH is increased using sodium hydroxide. The abrasive is then dispersed whilst the mix is subject to a full or partial vacuum. This effectively deaerates the mix. Surfactant is then dissolved in the mix followed by the solvent. Preferably high shear mixing of the solvent in the mix is used in order to form a stable microemulsion. Modes for Carrying Out the Invention In order to better understand the nature of the invention a number of examples of hard surface cleaners of the invention will now be described. In each case they were prepared using the method set out above. Cleaning performance was evaluated as follows:- Cleaning Performance

Plate cleaning experiments were performed using a 0.25 mm coating of synthetic dirt on a ceramic tile. The coating was prepared using a mixture of canola oil (mainly oleic acid)/soya oil (ca 50/50 oleic/linoleic acid)/carbon black (10:10:2). Tile and coating were baked for two hours at 125 C. This recipe/procedure is similar to that given in EP87308220.

The procedure for assessing cleaning performance on the above coating/tile was as follows:- - A Wettex brand sponge strip (ca 3 mm thick) is thoroughly wet with water, rung dry by hand and then clamped into a jig to expose a flat area, 15 cm x 7.5 cm, to the dirt surface.

15 gms of water are added evenly over this flat area of Wettex and then 10 gms of test mixture.

The prepared sponge is then placed onto the dirt surface, a 1.5kg weight placed on top of the supporting jig and the sponge moved manually or mechanically backwards and forwards across the dirt at about 60 passes/minute. The amount of soil removed is then subjectively assessed.

Viscosity was determined at 25 ± 0.1 C using a Brookfield LVT viscometer fitted with a No. 3 spindle at 60 rpm.

The refractive index matching component was prepared separately by simply mixing the indicated ingredients as indicated below.

EXAMPLES Refractive Index Adjusting Component

(Wt%) Mix No: Sucrose Urea Glycerol Water Refractive

Index

An appropriate amount of one of these components was included in each example hard surface cleaner in the indicated amounts.

HARD SURFACE CLEANERS

(Wt%)

Example No: 1 2 3 4 5 6 Ingredient Nansa SSA/L 2 2 2 2 2.5 3

Empilan FD 4.9 4.9 4.9 3.7 3.1 2.4

Limonene 3 3 3 3 3 3

Sident 15 10 10 10 10 10 10

Sodium Chloride - 0.047 0.47 0.47 0.47 0.47 R.I. Component 80.1 80.053 79.63 80.83 80.93 81.13 pH 10.5 10.5 10.5 10.5 10.5 10.5

Cleaning NT NT NT NT NT NT performance

Viscosity (cps) ND ND ND ND 552 ND

Example No: 7 8 9 Ingredient

Nansa SSA/L 1 2.5 2.5

Teric 12A6 5 4 4

Sident 15 10 10 10 Limonene 3 3 3

R.I. Component 81 80.5 80.5 pH 11.0 11 11.3

Cleaning performance NT NT NT

Viscosity (cps) 1600 1000 1600

NT - Not tested but expected to be satisfactory

ND - Not determined but judged qualitatively to be satisfactory.

*100% dirt removal after number of strokes given.

Nansa SSA/L - (dodecyl benzene sulphonic acid) - Trade Mark of Albright & Wilson

Empilan FD (82% coconut diethanolamide, 9% glycerol, 6.5% free diethanolamine) trade mark of Albright & Wilson Teric 12A6 (lauryl alcohol ethoxylate) Trade Mark of ICI

Teric 13A9 - (branched synthetic C._^-C,.-, alcohol ethoxylate) Trade Mark of ICI

Teric 16M5 (soya amine ethoxylate) Trade Mark of ICI Teric 17M5 (tallow amine ethoxylate) Trade Mark of ICI Sident 15 (silica) trade mark of Degussa - average aggregate size 6 micron, refractive index 1.45

Sident 12 (silica) trade mark of Degussa average aggregate size 15 micron, refractive index 1.45

Hostaflon (polytetrafluoroethylene 37 micron) trade TF9203 mark of Hoechst Tabs D (100% terpene hydrocarbon) obtained from Bush, Boake and Allen

Sucrose ester LWA 1570 (sucrose monolaurate) obtained from Mitsubishi-Kasei Food Corp.

Sodium lauryl sarcosinate - (75% active)

Examples 1-13, 15-25 included as R.I. component mix 7, whilst Example 14 included mix 071.

All Examples had satisfactory stability. It will be appreciated that whilst the hard surface cleaning compositions of the present invention have been described with reference to certain examples, it will be appreciated by those skilled in the art that numerous variations are possible without departing from the spirit or scope thereof.

Claims

CLAIMS : -

1. A clear hard surface cleaning composition in the form of a microemulsion comprising: a) 1 to 26wt% of an abrasive with a single value refractive index of not more than 1.477 which is dispersed in said composition; b) one or more anionic or nonionic surfactants selected from the group consisting of alkyl benzene sulfonates, saturated and unsaturated fatty acid soaps, amine oxides, sarcosinates, alkyl ethoxysulphates, betaines, alcohol ethoxylates, ethoxylated fatty amines, nonyl phenol ethoxylates, sucrose esters, alkyl glucosides and fatty acid alkanolamides, or mixtures thereof; c) sufficient of a component to adjust the refractive index of the continuous phase to that of the abrasive; d) one or more oil and grease solvents selected from the group consisting of hydrocarbons, cineole, terpene alcohols, terpene aldehydes, and terpene ketones, or mixtures thereof, in the dispersed phase; and e) water.

2. A composition as claimed in Claim 1 wherein the abrasive is selected from polytetrafluoroethylene and silica.

3. A composition as claimed in claim 2 wherein the abrasive is silica having a refractive index of about 1.45.

4. A composition as claimed in Claim 2 wherein the abrasive is polytetrafluoroethylene having a refractive index of about 1.370.

5. A composition as claimed in Claim 3 wherein the concentration of silica is in the range of from 8 to 16wt%.

6. A composition as claimed in Claim 5 wherein the concentration of silica is in the range of from 10 to 13wt%.

7. A composition as claimed in Claims 3, 5 or 6 wherein the average aggregate size of the silica is in the range of from 0.01 to 75 microns.

8. A composition as claimed in Claim 7 wherein the average aggregate size of the silica is up to 20 microns.

9. A composition as claimed in Claim 8 wherein the average aggregate size of the silica is in the range of from 6 to 13 microns.

10. A composition as claimed in any of the preceding claims wherein the refractive index adjusting component comprises an aqueous solution of t-butyl alcohol, glycerol, sorbitol, urea, lactose or sucrose.

11. A composition as claimed in Claim 10 wherein the refractive index adjusting component comprises a mixture of sucrose, urea, glycerol and water.

12. A composition as claimed in Claim 11 wherein the refractive index adjusting component comprises up to 35wt% sucrose, 25 to 45wt% urea, 5 to 35wt% glycerol and the balance water.

13. A composition as claimed in any one of the preceding claims wherein the anionic surfactant is selected from the group consisting of dodecylbenzene sulfonate, sodium oleate, sodium laurate, lauryl dimethylamine oxide, cocodimethylamine oxide, sodium lauryl sarcosinate and cocoamidopropyldimethyl amine oxide.

14. A composition as claimed in any one of the preceding claims wherein the nonionic surfactant is selected from the group consisting of linear alcohol ethoxylates, sucrose oleate, sucrose monolaurate, alkyl dextrose, sodium coco-hydrolysed animal protein, dodecyl ether of maltose, octyl ether of glucose and coconut diethanolamide.

15. A composition as claimed in Claim 13 or Claim 14 comprising a mixture of anionic and nonionic surfactants.

16. A composition as claimed in Claim 15 comprising a mixture of alkyl benzene sulfonate and either a linear alcohol ethoxylate or a fatty acid diethanolamide.

17. A composition as claimed in any one of the preceding claims wherein the surfactant concentration is in the range of 1 to 10wt%.

18. A composition as claimed in Claim 17 wherein the surfactant concentration is in the range of 3 to 7 wt%.

19. A composition as claimed in any one of the preceding claims wherein the oil and grease solvent is cyclohexane, decane, limonene, menthene, cumene, pinene or cineole, or mixtures thereof.

20. A composition as claimed in any one of the preceding claims wherein the concentration of the oil and grease solvent is not more than 10wt%.

21. A composition as claimed in Claim 20 wherein the concentration of the oil and grease solvent is less than 5wt%.

22. A composition as claimed in any one of the preceding claims wherein the viscosity is in the range of 500-3000cps when measured at 25° ± 0.1°C with a Brookfield LVT viscometer using a No 3 spindle at 60rpm.

23. A composition as claimed in Claim 22 wherein the viscosity is in the range of 800-2000cps when measured at 25 ± 0.1 C with a Brookfield LVT viscometer using a No 3 spindle at 60rpm.

24. A composition as claimed in any one of the preceding claims, excluding sucrose esters, having a pH greater than 9.0.

25. A composition as claimed in Claim 24 having a pH of from 10.5 to 11.5.

26. A composition as claimed in any one of claims 1 to 23, which includes sucrose esters, having a pH of from 6.0 to 8.0.

27. A method of forming a composition as claimed in any one of the preceding claims comprising (a) forming the refractive index adjusting component, (b) adjusting the pH, if necessary, with sodium hydroxide, (c) dispersing the abrasive in the mixture under at least partial vacuum, (d) dissolving the surfactant, (e) adding the solvent and mixing at high shear to form a stable microemulsion.