GB2247894A - Aerosol prewash cleaner - Google Patents

Abstract

An aerosol prewash cleaner composition is disclosed which has suppressed flammability. The composition is in the form of a water-in-oil microemulsion and includes -40-85% w/w of one or more hydrocarbon solvents; water in an amount of 1 - 12% w/w; 5 - 25% w/w of one or more nonionic surfactants; and as propellant dimethylether, in an amount of 8 - 25% w/w.

Description

PREWASH CLEANER COMPOSITION Afield of the Invent' on This invention relates to prewash cleaner compositions in the form of aerosols, more particularly to such compositions having suppressed flammability.

Background of the Invention Prewash cleaner compositions are used to treat textiles to selectively remove or enhance the removal of various soils that occur thereon. Typically these compositions are presented in aerosol form or in trigger dispensers to facilitate the application of the cleaner composition with some specificity to the soil affected area.

In use, a prewash cleaner composition is sprayed onto the soil affected area prior to the textile being laundered.

In the context of clothing textiles, it is perceived by consumers that collar and cuffs stains, which are sebaceous in nature, together with grease and oil stains are the most difficult to remove by normal washing methods. Accordingly, for elective cleaning performance, a suitable oil and grease solvent together with surfactant is required.

Although the prior art discloses numerous compositions of this type, for present purposes the discussion will be limited to aerosol compositions.

One difficulty that has been addressed in the prior art is the need to avoid the generation'of gases that will deplete the ozone layer around the earth. The chlorofluorocarbon propellants are a class of gases for which evidence exists to indicate that they are one of the classes of gases responsible for ozone depletion.

Accordingly, aerosol prewash cleaner compositions were developed wherein chlorofluorocarbon propellants were typically replaced with hydrocarbons, such as butane and propane.

However, hydrocarbon propellants are highly flammable and therefore it was desirable in these compositions to provide some flammability suppression.

One way in which flammability'was suppressed in these compositions was through the use of chlorohydrocarbon solvents. The use of such solvents had a double benefit in that flammability was suppressed whilst the chlorohydrocarbons functioned as efficient grease solvents.

Whilst the chlorohydrocarbons provided good cleaning performance, some of these compounds are also now suspected to contribute to the depletion of the ozone layer. For this reason, alternative grease solvents such as hydrocarbons have been used.

However, the combination of hydrocarbon solvent with hydrocarbon propellant results in a product that is very highly flammable. Thus, a product such as this when sprayed into a flame will have a very long and very hot flame. The flame is self-sustaining when taken away from the ignition source and it burns back to the actuator nozzle. Accordingly, while such products are not detrimental to the ozone layer and have effective cleaning performance, in use they are potentially quite dangerous.

Attempts have in the past been made to suppress the flammability of hydrocarbon solvent/hydrocarbon propellant formulations. Successful suppression has been achieved by formulating products as oil-in-water emulsions or oil-in-water microemulsions. Australian patent No. 574715 to Bristol-Myers Co. discloses a suppressed flammability formulation which is an oil-in-water microemulsion formulation.The formulation comprises a propellant composition having (a) 23 - 35% of a water-immiscible liquid which is a solvent for the propellant; (b) 15 - 25% water; (c) 3 - 20% of a mixed surfactant system of at least one low HLB and at least one high HLB surfactant, the mixed surfactant system having a hydrophilic lipophilic balance sufficient to cause the water-immiscible liquid in which the propellant is dissolved to disperse as micro-droplets in the water upon shaking of the aerosol dispenser; and (d) at least 30% by weight of the total weight of the composition of at least one normally gaseous flammable aerosol propellant provided to pressurise the aerosol dispenser. The resultant aerosol has suppressed flammability.

Australian patent 574715 teaches that suppressed flammability is achieved by virtue of the dissolution of the flammable propellant in the oil phase, which phase is present as dispersed microdroplets in the continuous water phase. On page 15a it is disclosed that the formulation can be used as a laundry pre-spotter composition.

However, while such formulations may have suppressed flammability, their cleaning performance particularly against oily stains is inferior. It is believed that the reason for this is as a result of the oil phase being the dispersed phase.

There are also formulations which are water based.

These rely on high levels of surfactant to achieve cleaning and again whilst having suppressed flammability, have inferior cleaning performance against oily stains.

The present inventors have recognised the substantial difficulties in the prior art and have sought to provide an aerosol prewash cleaner composition having suppressed flammability which has good cleaning performance, and avoids the use of solvents and propellants that are known or suspected of causing damage to the ozone layer.

Surprisingly, the present inventors have found that contrary to the teaching of Australian patent 574715, a formulation that is a water-in-oil microemulsion rather than an oil-in-water microemulsion will have suppressed flammability and good cleaning performance when based on the use of the propellant dimethylether. This is indeed an unexpected result particularly in view of the teaching of Australian patent No. 574715 and the specific disclosure therein in claim 20 of the use of dimethylether in the context of a "normally gaseous flammable propellant".

Summary of the Invention Accordingly, the present invention consists in an aerosol prewash cleaner composition having suppressed flammability comprising: - one or more hydrocarbon solvents, wherein the total amount of hydrocarbon solvent is 40 - 85% w/w; water, in an amount of 1 - 12% w/w; one or more nonionic surfactants, wherein the total amount of nonionic surfactant is 5 - 25% w/w; and as propellant dimethylether, in an amount of from 8 - 25% w/w; said composition being in the form of a water-in-oil microemulsion.

Description of the Invention From the foregoing, it will be evident that whilst the present invention has suppressed flammability and has ingredients in common with the composition disclosed in Australian patent No. 574715, not only are the compositions in different states of emulsification but the concentrations of a number of the ingredients are different. Thus, the minimum amount of water in 574715 is 15 whilst the maximum in the present invention is 12%. The maximum amount of solvent in 574715 is 35 whilst the minimum in the present invention is 40%. At least 308 of 574715 composition is propellant whilst the present invention uses at most 25%.

Therefore, given that the concentration ranges of ingredients in the present composition must be maintained within the specified limits to achieve a product in the form of a water-in-oil microemulsion having suppressed flammability and good cleaning performance, it is apparent that Australian patent 514715 does not disclose or suggest the present invention.

Furthermore, the prior art compositions based on chlorohydrocarbon solvents and hydrocarbon propellants are fundamentally different to the composition of the present invention notwithstanding that potentially dimethylether could be used as a substitute propellant. This difference is that water must be rigorously excluded from these prior art compositions or otherwise hydrochloric acid is generated due to hydrolysis of the chlorohydrocarbons.

The presence of hydrochloric acid has a highly corrosive effect on aerosol cans.

A variety of hydrocarbon solvents may be used such as the isoparaffins and white spirit. Although the concentration of the solvent may range from 40 - 85% w/w, a range of from 50 - 85% w/w is preferred. It will be appreciated that mixtures of hydrocarbon solvents may be used.

The concentration of water in the composition is critical in that it aids to reduce flammability. This is thought to occur by virtue of water miscibility with the dimethylether and the nonionic surfactant. In the concentration range used in this composition, 1 - 12% w/w, the water is present in the form of microdroplets dispersed throughout the continuous oil phase.

If the concentration of water is increased above 12%, the resultant composition will not be a microemulsion and hence will lack stability. Rather, the composition will tend to form a milky emulsion which will be susceptible to separation into separate oil and water phases. Such separation will have adverse consequences both in production and in use. In production where typically a concentrate is prepared and stored prior to filling with propellant into aerosol cans, the relative concentration of ingredients in the aerosol could well be outside the required ranges. Hence the cleaning performance and flame suppression will likely be adversely effected.

Similarly, if separation of the product occurs in the aerosol can, a composition will be dispensed which does not have the required cleaning properties with suppressed flammability.

If on the other hand the concentration of water is too low, flame suppress ion will be minimal and unacceptable.

The present inventors have found that a preferred concentration range of water is from 2 - 7% w/w.

At least one nonionic surfactant is included in the inventive composition. A variety of nonionic surfactants may be used of which fatty alcohol ethoxylates are preferred. These are widely and readily available and the person skilled in the art would readily recognise those surfactants that are suitable to maintain the composition in the form of a water-in-oil microemulsion.

It must also be recognised that the surfactants also function in cleaning.

A preferred range of concentration of nonionic surfactant(s) is 10 - 20% w/w.

In order to obtain the requisite flammability suppression, dimethylether must be used as the propellant in an amount of from 8 - 25% w/w. Although dimethylether when compared with butane is known to be less flammable, have a lower combustion heat output, and to have a higher lower explosion limit, its choice as a propellant for this composition is not an obvious one. Thus, it is still regarded as a flammable propellant and due to its high pressure it would be expected to have a long flame length. Furthermore, in all other regards, the prior art teaches its equivalence to a variety of other flammable propellants.

The compositions of the invention may include other ingredients such as corrosion inhibitors, perfumes and the like. The person skilled in the art would recognise such additives and be able to readily determine the concentration in which they are to be used.

The compositions of the present invention have suppressed flammability in that when sprayed into a flame and then removed from the ignition source, the flame is barely self-sustained and does not burn back to the actuator nozzle. This is in marked contrast to the hydrocarbon solvent/hydrocarbon propellant prior art compositions. Furthermore, it is equal to if not better than prior art compositions based on chlorohydrocarbon solvents/hydrocarbon propellants.

In order to obtain maximum suppression of flammability and to optimise spray characteristics, the valve and actuator combination used in the aerosol dispenser may be varied. The person skilled in the art without having to resort to undue trial and experimentation would be able to readily select a suitable combination of valve and actuator.

The compositions of the present invention may be readily prepared in the following manner:1. The surfactant is dissolved in the hydrocarbon solvent.

2. Water is added to the surfactant solution and stirred until clear.

3. Additives such as corrosion inhibitors and perfume are then added with stirring.

4. The resultant concentrate is then filled into aerosol containers using the requisite amount of dimethylether.

In order to better understand the nature of the present invention, a number of examples are set out below. All of the examples were prepared as described above.

Example 1 Ingredient % w/w Isoparaffin solvent 68.5 Teric Gl2A6 C12-14 fatty alcohol ethoxylate (6 moles ethylene oxide) 12.0 Deionised water 2.0 Perfume 0.3 Corrosion inhibitor 0.2 Dimethyl ether propellant 17.0 Example2 White spirit solvent 59.6 Teric G12A4 Cl2-14 fatty alcohol 18.0 ethoxylate (4 moles ethylene oxide) Deionised water 5.0 Perfume 0.3 Corrosion inhibitor 0.1 Dimethylether propellant 17.0 Example 3 White spirit solvent 59.6 Teric G12A4 C12-14 fatty alcohol ethoxylate (4 moles 14.0 ethylene oxide) Teric G12A8 C12 -14 fatty alcohol ethoxylate (8 moles 4.0 ethylene oxide) Deionised water 5.0 Perfume 0.3 Corrosion inhibitor 0.1 Dimethylether propellant 17.0 Teric G12A6, G12A4 and G12A8 are trade marks of ICI.

A number of comparative examples of prior art compositions were prepared as follows; Example 4 Ingredient % w/w White spirit solvent 64.7 Nonionic surfactants as Example 3 18.0 Perfume 0.3 Hydrocarbon H40 propellant 17.0 Example 5 White spirit solvent 61.7 Mineral turpentine 3.0 Nonionic surfactant as Example 3 18.0 Perfume 0.3 Hydrocarbon H40 propellant 17.0 Example 6 1,1, 1-Trichloroethane solvent 49.7 White spirit solvent 12.0 Mineral turpentine 3.0 Bionic STP 18.0 Perfume 0.3 Hydrocarbon H40 propellant 17.0 Bionic STP is a proprietary blend of nonionic surfactants and is a trade mark of ICI.

The cleaning performance of Example 3 and comparative Example 6 were evaluated using the following protocol: The test results are set out in Tables 1 and'2.

1. FABRIC White polyester/cotton 65/35 Cotton 100% 2. WASHING CONDITIONS 2.1 Hoover 635 top loading automatic washing machine, 12 minute wash, 2 rinses.

2.2 Wash temperature: Cold, record actual temperature 2.3 Detergent: 96g of powder detergent - Omo, Fab or equivalent - per low fill (1.5g/L).

2.4 Only test and control swatches are washed in machine, no dummy load.

2.5 Swatches are dried in tumble dryer before evaluation.

3. STAYS Test stains: Sump oil (applied to soak approx 80mm circle) Engine grease (applied in 50mm circle) Biro, blue (applied approx aver 10 X 50mm area) Texta pen (applied over 10 X 50mm area) (solvent based felt pen) Lipstick, red (applied aver 10 X 50mm area) (record brand used) Shoe polish, black (dabbed lightly onto 25mm (record brand used) circle) Clay (applied to approx 10 X 50mum area) Grass (applied to approx 10 X 50mm (juice ex blended area) fresh grass cuttings) Red wine (applied to soak approx 80 Tmn (Record type and brand circle) used) Black coffee (applied to soak approx 80mm (Record type and brand circle) used) White tea (applied to soak approx 80mm (Record type and brand circle) used) Each of these stains are categorised as follows:- Grease and oil: Sump oil, engine grease, red lipstick, black shoe polish Proteinaceous: Grass Bleacbable: Blue Biro, Texta pen, red wine, black coffee, white tea Particulate:Clay Fabric swatches are to be washed according to washing conditions given above prior to staining.

Always prepare one set of stains more than number of samples to be evaluated and wash without prewash treatment. Select swatches randomly for samples to be evaluated.

4. TIMING Standard time between staining and application is 24 hours.

5. RATING a) Stains are rated on a 0-5 scale. 0 indicates complete removal of stain, 5 indicates no removal of stain.

b) Stains are rated by two experienced people, who agree on a rating between them. As a check, stains can be rated independently on two different days.

c) Stains are rated in strong "south" daylight (would be north light in northern hemisphere). White swatches are laid flat on a dark background for rating; this procedure makes rating easier and more reproducible, especially for oil stains.

6. TEST DESIGNS a) This varies depending on the aim of the test. Extra parameters such as age of stain or washing conditions can be varied if necessary.

b) An "untreated" control stain is always washed in the same load as each sample tested with prewash. A number of different stains are tested in the same washload (along with their corresponding "untreated" controls) but only one prewash product is tested in the one washing machine load.

c) Wherever possible, ratings are only compared within the one set of trials.

TABLE I Cleaning Performance - 100% Cotton Rating Stain Example3 Example6 Test 1 2 3 Test 1 2 3 Grease and oil 2.5 1.3 2.1 2.1 1.9 2.3 Proteinaceous 1.3 3.8 3.0 1.4 3.8 1.5 Bleachable 2.5 3.5 2.8 1.8 2.7 2.4 Particulate 2.8 4.2 2.3 2.5 4.0 2.0 TABLE 2 Cleaning Performance - 65g35 Polyester Cotton Rating Stain Example 3 Example 6 Test 1 2 3 Test 1 2 3 Grease and oil 2.0 2.5 1.8 1.7 , 3.2 2.9 Proteinaceous 2.0 2.8 2.8 2.0 1.8 2.5 Bleachable 2.6 3.2 2.9 2.1 2.5 2.1 Particulate 2.0 3.3 1.5 2.0 3.3 1.5 From these test results, it is evident that Example 3 had at least equivalent cleaning performance to comparative Example 6.

The flammability of Example 3 and the Comparative Examples 4-6 was determined according to the Flame Propagation test set out in Australian Standard 2278-1986. The results are set out in Tables 3 and 4.

Table 3 Flame Propagation - Example 3 Flame length (mm) Sustain Burnback Temp.

Full can 450-500 no no mild Half full can 450-500 no no mild Quarter full can 450-500 slight no very mild Table 4 Flame Propagation - comparative Examples Flame length (mm) Sustain Burnback Temp.

Example 4 about 500 yes yes hot + voluminous Example 5 about 500 yes yes hot + voluminous Example 6 450-500 yes no N/A Whilst these results for the comparative examples are for tests obtained using full cans, similar results are obtained when half and quarter full cans are tested.

From these results, it is evident that the flammability of the Example 3 is lower than that of the prior art comparative examples.

Although the present invention has been described with reference to certain preferred embodiments and examples, it will be appreciated by those skilled in the art that numerous variations and modifications are possible without departing from the spirit or scope of the invention.

Claims (7)

Claims

1. An aerosol prewash cleaner composition having suppressed flammability comprising: one or more hydrocarbon solvents, wherein the total amount of hydrocarbon solvent is 40-85% w/w; water, in an amount of 1-12% w/w; one or more nonionic surfactants, wherein the total amount of nonionic surfactant is 5-25%; and as propellant dimethylether, in an amount of 8-25 w/w; said composition being in the form of a water-in-oil microemulsion.

2. A composition as claimed in Claim 1 wherein the total amount of hydrocarbon solvent is 50-85 w/w.

3. A composition as claimed in Claim 1 or Claim 2 wherein the water is present in an amount of 2-7 w/w.

4. A composition as claimed in any one of Claims 1 to 3 where the total amount of nonionic surfactant is 10-20% w/w.

5. A composition as claimed in any one of Claims 1 to 4 wherein there are two nonionic surfactants present.

6. A composition as claimed in any one of Claims 1 to 5 wherein when only one nonionic surfactant is present it is an ethoxylated fatty alcohol and when two or more nonionic surfactants are present at least one of them is an ethoxylated fatty alcohol.

7. An aerosol prewash cleaner composition having suppressed flammability and being in the form of a microemulsion substantially as hereinbefore described with reference to any of Examples 1, 2 or 3.