EP0694061B1

EP0694061B1 - Hygienic cleaning composition and apparatus for spraying said composition

Info

Publication number: EP0694061B1
Application number: EP94914381A
Authority: EP
Inventors: Brian George Humfress; Joanna Mary Jones; Helen Martin; Cheryl Mcgrath
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 1993-04-15
Filing date: 1994-04-12
Publication date: 1997-07-02
Anticipated expiration: 2014-04-12
Also published as: PL176537B1; PL311085A1; EP0694061A1; SK280780B6; WO1994024259A1; SK125295A3; GB9307804D0; HU9501989D0; ZA942580B; DE69404032D1; CZ283899B6; ES2103586T3; HU216801B; CZ265995A3; HUT72729A; AU6678394A; TR28732A

Abstract

A known problem with hygienic cleaning sprays is the formation of airborne irritant droplets, either as a direct result of spraying a fine mist or due to the impact of a jet on a hard surface. The user is often advised to spray the product onto a cloth for subsequent application onto the surface. Use of a cloth or sponge in this manner detracts from the convenience of using a spray. By including surfactant in the product and using a spray head which contains a plurality of apertures disposed so as it is possible to produce a spray of foam droplets rather than produce a jet, mist of droplets or aerosol. Accordingly, the present invention provides an aqueous, liquid, hypo-chlorite-containing cleaning composition comprising, 0.05 % wt - 3.0 % wt aqueous alkali metal hypochlorite, 0.1 % wt - 5.0 % wt of a hypochlorite-stable surfactant, said composition being packaged in a container adapted to produce a spray of foam droplets.

Description

Field of the Invention

The present invention relates to a hygienic cleaning composition packaged in a container adapted to produce a spray.

Background to the invention

Hygienic cleaning compositions always have some type of anti-microbial activity and in particular generally have an anti-bacterial activity. Hard-surface cleaning compositions in commercial use as hygienic cleaning compositions for sanitary porcelain, work-surfaces, white goods and the like can be classified into two groups, hypochlorite-based products and hypochlorite-free products.. In general, these products are liquids.
Hypochlorite-free products comprise a variety of aqueous acids, quaternary ammonium salts, peroxy acids and solvents as the anti-microbial agents. The efficacy of these products varies with the type of anti-microbial agent used. Quaternary ammonium compounds and peroxy acids are general biocides. Solvents and aqueous acids are less effective especially against spore-forming bacteria. In general, commercial hypochlorite-free cleaning compositions are less effective against moulds, fungi and yeasts than similar compositions which contain hypochlorite.
Hypochlorite-based products generally contain aqueous sodium hypochlorite. Hypochlorite is known to be the one of the most effective hygiene agents, especially at low concentrations, and is available in commercial quantities at acceptable cost. Hypochlorite is an effective hygiene agent, providing a hygiene benefit against a wide range of microbes including bacteria, moulds, yeast and fungi.
Hypochlorite cleaning compositions typically contain, in addition to the hypochlorite, one or more surfactants. The choice of these surfactants is limited by the reactive chemistry of hypochlorite solutions. Surfactants used in hypochlorite solution are generally amine oxides and/or water soluble alkyl sulphates, although certain betaines and soaps have also been used. In general terms, the surfactants present in hypochlorite solutions must be free of readily oxidisable groups. In some products, these surfactants are present to improve cleaning performance. In other products, these surfactants are present as a part of a thickening system. Typical concentrations of hypochlorite, in solution, have ranged from 1-15%wt: with concentrations towards the lower end of this range (less than 3%wt) being used for general purpose hygienic cleaners which find utility in both kitchens and bathrooms.
Hypochlorite and hypochlorite-free cleaning compositions have traditionally been delivered to surfaces by use of a carrier such as a cloth or sponge onto which the composition is poured or which is dipped into a solution of the composition. This mode of application results in some wastage of the product due to absorbtion onto the cloth or sponge.
More recently, liquid, hypochlorite-free products have been provided in a package adapted to produce a fine spray (aerosol) or jet of the product to facilitate delivery to a surface. Typical spray heads comprise a single, relatively small, aperture to which product is fed by pump means operated by a trigger mechanism. The deciding factors in determining whether a particular spray head will produce a mist or a jet include product properties, spray aperture geometry and spray pressure.
Known problems with sprays are the formation of airborne irritant droplets, either as a direct result of spraying a fine mist or due to the impact of a jet on a hard surface. Consequently, in the instructions for use of certain products, especially those containing relatively high levels of hypochlorite, the user is recommended not to spray the product directly onto a surface but rather to spray onto a cloth for subsequent application onto the surface. Use of a cloth or sponge in this manner detracts from the convenience of using a spray.
JP-A-62/286000 (filed 4th June 1986 as JP 129852/86) of Unicharm K.K. describes sprayable, foaming, liquid, detergent compositions which comprise hypochlorite, an alkali, a hypochlorite stable surface active agent, and a solvent. The solvent is particularly characterised as being a linear polyethylene glycol or linear polypropylene glycol which is methyl-capped at both ends of the molecule. Preferred solvents include those with a short glycol chain. It is believed that the presence of this specific class of solvent promotes the formation of a stable foam on the surface to be cleaned and that this foam prevents the release of chlorine from the foam into the ambient.
It is believed that while the above-mentioned Japanese publication teaches how a reduction may be achieved in release of chlorine at the surface to which the composition is applied, it does not solve the problem of the formation at the point of spraying of a fine mist or aerosol which causes respiratory and other wet-tissue irritation. This irritation is believed to be due both due to the hypochlorite present in the droplets and the presence of the particular surfactants which are required (i.e. stable) in the presence of hypochlorite.
EP-A-0298172 discusses the problem of fine mist formation. The document suggests that the problem is solved by the specific use of a viscoelastic surfactant': these surfactant systems are said to form a minority among all surfactant species. The surfactants which are employed in the citation all have hexadecyl-trimethyl ammonium bromide as the hydrophobic species and either sodium p-toluene sulphonate or sodium 3,4-dichlorobenzoate as the hydrophilic species.
US-A-4228048 discloses a foam cleaner for food plants which comprises 0.05-5.0wt% hypochlorite, with examples at 1.4% hypochlorite on product. The product further comprises n-alkane sulphonate (8.0%), commonly known as SAS. There is no suggestion in this citation that the product should be delivered in the form of a spray of foamed droplets as foam cleaning apparatus produces a stream of uniform foam which pours from the apparatus directly onto the surface which is thereby coated with the foam.

Brief Description of the Invention

We have now devised a hypochlorite-containing product, packaged in a container adapted to produce a spray which has a reduced tendency to cause respiratory irritation. We have accomplished this by including surfactant in the product and using a spray head which contains a plurality of apertures disposed so as to produce a spray of foam droplets rather than produce a jet, mist of droplets or aerosol. For the purposes of the present invention 'foam' droplets are droplets having air entrained therein.
Accordingly, the present invention provides a device comprising the combination of:

1) a container adapted to discharge a cleaning composition in the form of a spray of foam droplets, with;
2) within the container, an aqueous, hypochlorite-containing cleaning composition comprising:
- a) 0.05%wt-3.0%wt aqueous alkali metal hypochlorite; and,
- b) 0.1%wt-5.0%wt of a hypochlorite-stable surfactant, which comprises one or more alkyl sulphonates;
  wherein, the composition (2) is discharged from the container (1) in the form of a spray of foam droplets.

It is believed that an advantage of the present invention is that the product can be sprayed directly onto a surface and the use of a cloth or sponge as a carrier can be avoided. Moreover, the compositions of the present invention do not require the solvent of JP-A-62/286000 to be present in order to prevent droplets being formed at the surface being treated by spraying.

Detailed Description of the Invention

As mentioned above, the use of a spray head which forms droplets of foam avoids the formation of a fine mist of liquid droplets either through the direct action of the spray head or as a result of the impact of the product on a hard surface. This requires the presence of a suitable surfactant which is both foaming and sufficiently stable in the presence of the levels hypochlorite found in the product to give an acceptable shelf life. Further details on the preferred features of the invention are given below.

Hypochlorite

Hypochlorite is an essential component of the composition according to the present invention.
The preparation and handling of hypochlorite solutions are well known in the art. Preferred levels of hypochlorite range from 0.15-2.0%wt on product. Lower levels of hypochlorite are less effective whereas the risk of respiratory irritation increases with higher concentrations of hypochlorite. Hypochlorite levels of 0.15-1.0%wt, particularly 0.2-0.4wt% are preferred as this provides sufficient hypochlorite to provide a hygiene benefit without a serious risk that respiratory irritation will occur.
The presence of additional hygiene agents, other than hypochlorite, in the compositions of the present invention is not intended to be excluded.

Surfactant

A hypochlorite-stable alkyl sulphonate surfactant is an essential component of the cleaning composition according to the present invention. It is important that this surfactant foams to the extent necessary to form foam droplets when sprayed.
More preferably, the surfactant is a secondary alkyl sulphonate. We have determined that while secondary alkyl sulphonate can be irritant when sprayed in a fine mist, it is particularly well adapted to the formulations of the present invention where such a fine mist is not formed.
Particularly preferred secondary alkane sulphonates comprise a mixture of materials of the general formulation:
wherein R₁ and R₂ are the same or different, each being a straight or branched chain alkyl group having at least one carbon atom, the alkyl chain length being in the range 13-18, and X is a solubilising cation.
Preferably the surfactant level is 1-3wt% on product. Lower levels of surfactant reduce cleaning efficiency whereas higher levels of surfactant can lead to an increased incidence of respiratory irritation. Surfactant levels of around 2%, i.e. 1.5-2.5% are particularly preferred as these provide sufficient cleaning and foaming effect without excessive use of surfactant.

Spray Head

It is essential that composition according to the present invention is packaged in a container adapted to produce a spray of foam droplets.
Preferably, the spray comprises less than 1000 micrometer/m³ of droplets having a particle size of less than 7 micrometer. More preferably, the spray contains less than 500 micrometer/m³ of droplets having a particle size of less than 7 micrometer.
The current UK legal limit for irritant/nuisance dust and gasses is 500 mg/cubic litre. For the purposes of this specification potentially irritant droplets are considered to have a droplet size of less than 7 micrometer.
As will be illustrated hereafter with reference to specific examples, not all spray heads are capable of producing a foam. Several modifications can be made to the conventional, single aperture, spray head described above to ensure that a foam is formed and modified spray heads are commercially available.
In a typical foam-forming spray head, such as that employed in the AFA 7585-4 [ex. SPRAYCHEM Ltd] bottle cap, the product is delivered to the spray head by conventional trigger-operated pump-means and ejected via a plurality of apertures comprising a grid-like plate to form a number of streams which recombine so as to entrain air within the droplets formed and thereby produce a foam.
Other designs of foaming trigger spray head are known, being designed to deliver hypochlorite-free cleaning compositions to a surface. Many of these alternatives share the common feature of having a plurality of apertures through which the product is dispensed.
It is preferable that the spray head is detachable from the body of the container in which the composition of the invention is stored so that an empty body may be replaced by a full one.

Stabilizers

Stabilizers are preferably present to prevent or retard decomposition of the hypochlorite during storage. Suitable stabilizers include transition metal sequestering agents, preferably selected from the group comprising, alkaline alkali metal silicates, phosphonates, periodates and mixtures thereof.
A particularly preferred stabilizer comprises sodium silicate at a level of 0.1-0.5%wt on product. This is effective as a metal sequesterant in alkaline solutions.

pH

Preferably, products according to the present invention are alkaline, more preferably of a pH of 10-13, most preferably, 11-12. This pH is conveniently attained by the inclusion of a strong alkali such as sodium hydroxide. It is preferred that compositions according to the present invention comprise around 0.1%wt alkali metal hydroxide.

Minors

Other, inessential components of the formulation according to the present invention can include a colouring agent comprising one or more copper phthalocyanides. Compositions according to the present invention can further comprise one or more of perfumes and solvents.
In order to facilitate processing, and particularly packing of the compositions according to the invention, it is convenient that formulations comprise an initial, low level of a hypochlorite-sensitive antifoam component which is decomposed during storage of the product. Silicones are particularly suited as hypochlorite sensitive antifoams.
Having regard to the foregoing, typical embodiments of the present invention comprise:

a) 0.05%wt-3.0%wt aqueous alkali metal hypochlorite,
b) 0.1%wt-5.0%wt of a hypochlorite-stable alkyl sulphonate surfactant, and,
c) an effective amount of a sequesterant for transition metal ions,

³

In order that the present invention may be further understood it will be explained herein after with reference to the following non-limiting examples.

EXAMPLES

A composition according to the present invention was prepared from the components as listed in Table 1 below. Components are identified as follows:

SAS:: Secondary alkyl sulphonate [HOSTAPUR 30-X, ex. Hoechst, RTM], received as 30% active solution.
Silicate:: Sodium silicate solution [CLAYSIL ex. CROSSFIELDS of Warrington], supplied as 100 Twaddle, comprising 18% NaOH, 28% silica.
Perfume:: Commercially available perfume, ex. International Flavours and Fragrances.
NaOH:: NaOH ex. ICI: supplied as 47% liquor.
Hypo:: Sodium Hypochlorite solucion 14-15% av. Cl₂, 12-13% NaCl, ex. ICI.
Silicone:: DB-100 ex. DOW [RTM]: hypochlorite sensitive antifoam.

Components were mixed by adding half the batch water into a stirred mixing vessel at a temperature of 50-60 Celsius: adding SAS, silicate, perfume, NaOH and silicone to the heated water, quenching with the balance of the water to around 30 Celsius and adding hypochlorite finally. TABLE 1

COMPONENT Wt% ON PRODUCT

SAS 2%

Silicate 0.107%

Perfume 0.21%

NaOH 0.08%

Hypochlorite 0.2% av C1₂

Silicone 0.01%

Water to 100%
The composition was packaged in a plastic container provided with a trigger spray head type AFA 7585-4, ex. SPRAYCHEM Ltd.
In order to demonstrate the advantages of the compositions according to the present invention, spraying experiments were performed to compare the potential for respiratory irritation of the present invention with that of other products. Compositions were sprayed, using the specified trigger head and ten trigger operations, in a 512 liter glove-box provided with an air inlet and an air outlet, onto a vertical metal surface from a distance of 10-30 cm. The particle size distribution of the airborne particles scattered within the chamber was monitored over five minutes in drawn-off air samples. Results are given in Table 2 below, for commercially available products, embodiments of the invention and other comparative examples.
Results as presented in Table 2 are given as 'RC': the concentration of particles having a mean size below 7 microns in micrograms per cubic metre.
'Embodiment 1' is the composition of table 1 and the RC is that obtained using the AFA 7585-4 spray head mentioned above. The 'comparative' example is the composition of Table 1 using a commercially available dual mode trigger head (T-8100 ex. Continental Sprayers Inc.) in the non-foam producing spray mode, whereas 'embodiment 2' is the same dual mode spray head in the foaming mode.
Embodiment 3 is the composition given in Table 1 with the addition of a further 0.2%wt SAS (a 10% increase in surfactant). Embodiment 4 is the composition given in Tabie 1 with the addition of a further 0.02%wt available chlorine as hypochlorite (a 10% increase in hypochlorite). In embodiment 5 the levels of both surfactant and available chlorine were increased 10%.
The commercial products are hypochlorite-free compositions used with the sprays as supplied with the product.

VIF BATHROOM and CIF MULTIUSO are commercially available neutral and acidic cleaners and are essentially free of strongly biocidal components. The packaging of the 'Brand-X' product advises that the product should not be sprayed directly onto a hard surface, but should be sprayed onto a cloth for subsequent application: this product is believed to contain a quaternary ammonium compound as a biocide. The 'Brand-Z' composition is believed to contain relatively low levels of potentially respiratory-irritant components and to contain solvents; i.e. the product is relatively free of strongly biocidal components.

TABLE 2

TRIGGER	RC.	%avC1 ₂
Embodiment 1	209	0.2%
Comparative	1834	0.2%
Embodiment 2	529	0.2%
Embodiment 3 (+SAS)	176	0.2%
Embodiment 4 (+Hypo)	158	0.22%
Embodiment 5 (+SAS/Hypo)	165	0.22%

VIF BATHROOM (RTM)	433	0
CIF MULTIUSO (RTM)	566	0
Brand-X	8772	0
Brand-Z	9774	0

From the results given in Table 2 it can be seen that the compositions of the present invention, in combination with the foam producing spray head, have a low potential to cause respiratory irritation. The 'comparative' example produces a potentially irritant droplet cloud, and the commercially available products, which are generally free of irritants show varied droplet sizes but due to the absence of available chlorine as hypochlorite would be expected to have poor germ-kill as compared with the compositions of the present invention.
In order to demonstrate this, a suspension test was performed with a composition according to the present invention and a range of commercially available spray cleaners similar to those mentioned above. The results of suspension tests are given in Table 3 below.
Evaluation was performed in the presence of both high (1.00% BSA) and low (0.03% BSA) as a soil model for each of five microbial species. Results quoted are for the final log concentrations of the microbes. 'k' indicates a complete kill. Brand-X is believed to contain a quaternary ammonium compound as a biocide and the package instructions advise the use of a sponge or cloth for application. Brand-Y is believed to contain relatively low levels of potentially respiratory-irritant components but is believed to contain solvents and be relatively free of strongly biocidal components.
From the above-mentioned results it can be seen that the composition of the present invention and 'Brand-X' achieved a complete germ-kill, whereas 'Brand-Y' did not exhibit such marked antimicrobial or germicidal properties. It is noted that the composition of the present invention and 'Brand-Y' could be applied directly, whereas 'Brand-X' required the use of a cloth or sponge. Thus, the hypochlorite products of the present invention provide for complete kill of the entire range of microbial populations while reducing hazard and inconvenience to the user: a combination of properties not exhibited by the prior art.

Claims

A device comprising the combination of:
1) a container adapted to discharge a cleaning composition in the form of a spray of foam droplets, with;

2) within the container, an aqueous, hypochlorite-containing cleaning composition comprising:
a) 0.05%wt-3.0%wt aqueous alkali metal hypochlorite; and,

b) 0.1%wt-5.0%wt of a hypochlorite-stable surfactant, which comprises one or more alkyl sulphonates;

wherein, the composition (2) is discharged from the container (1) in the form of a spray of foam droplets.
Device according to claim 1 wherein the hypochlorite content ranges from 0.15-2.0%wt on the composition.
Device according to claim 1 wherein the surfactant comprises a mixture of materials of the general formulation:
wherein R₁ and R₂ are the same or different, each being a straight or branched chain alkyl group having at least one carbon atom, the alkyl chain length being in the range 13-18, and X is a solubilising cation.
Device according to claim 1 wherein the composition further comprises one or more transition metal sequestering agents.
Device according to claim 1 wherein the composition has a pH of 10-13.