EP0811053B1

EP0811053B1 - Process and composition for cleaning surfaces

Info

Publication number: EP0811053B1
Application number: EP96901798A
Authority: EP
Inventors: Howard Anthony Barnes; Michael Joseph Garvey; Matthew James Leach; Martin Sharples; Gillian Smith
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 1995-02-23
Filing date: 1996-02-07
Publication date: 1999-05-06
Anticipated expiration: 2016-02-07
Also published as: IN186941B; HUP9801683A2; TW364923B; DE69602355T2; WO1996026263A1; CA2211166A1; KR19980702442A; ES2131928T3; AR001005A1; JPH11500480A; MY111862A; EP0811053A1; CN1175975A; TR199700839T1; HUP9801683A3; DE69602355D1; AU716833B2; AU4623196A

Description

Field of the Invention

The present invention relates to a process and composition for cleaning surfaces.

Background to the Invention

It is known to apply cleaning compositions containing surfactants, to surfaces, by spraying droplets of the composition onto a surface. In known spraying processes the film of composition deposited on the surface is continuous over a large part of its area, although, towards the edges of the spray pattern a discontinous field of droplets may be observed. This manner of application enables the product to be targeted in the region of the surface at which it is required. The spraying apparatus, such as so-called 'trigger pumps' which are used to deliver cleaning compositions generally deliver large doses of product in the form of relatively large droplets which flow and coalesce on surfaces so as to form a continuous film of the composition.

It is also known to spray foams, which are by definition not homogeneous on a small scale, onto a surface. Again, the trigger pumps which are used to deliver compositions in this form are known to deliver relatively large quantities of product.

Brief Description of the Invention

We have determined that when products comprising aqueous solutions of nonionics or nonionic/solvent systems are sprayed as fine droplets to form a discontinuous film, either less cleaning effort can be used with the same level of product, or the same effort can be used with less product. It is believed that the effect is due to the presence of an increased number of menisci and evaporation of the aqueous liquor or part of any solvent component from the product on the surface. It is further believed that this evaporation, especially at menisci, causes local increases in concentration and/or local turbulence which enhances the cleaning process. We have determined that a similar effect can also be observed with foams.

Detailed Description of the Invention

Accordingly, a first aspect of the invention provides a packaged, aqueous or solvent-containing, nonionic cleaning composition, in a container provided with a spray jet adapted to deliver the composition to a surface in the form of a spray, characterised in that the dosage applied to the surface by each operation of the spraying apparatus falls in the range 0.15-0.5ml and the said dose is applied over an area of at least 50 cm2 when the spray jet is operated 15cm from the surface.

A second aspect of the invention relates to a process for cleaning a hard surface which comprises the step of spraying a composition comprising a nonionic surfactant from a container provided with a spray jet, onto a surface in the form of a spray, characterised in that the dosage applied to the surface by each operation of the spraying apparatus falls in the range 0.15-0.5ml and the said dose is applied over an area of at least 50 cm2 when the spray jet is operated 15cm from the surface.

As mentioned above, is believed that by spreading the product on the surface in the form of discrete droplets and/or a foam which does not form a continuous film, a meniscus cleaning effect is promoted which assists the cleaning process. It is an important feature of the present invention that coalescence of the product on the surface to form a continuous film should be minimised, although it will be appreciated that some coalescence can occur.

Typically, the dosage applied to the surface by each operation of the spraying apparatus falls in the range 0.2-0.4ml: dosages of 0.25-0.35ml are particularly preferred. Prior-used sprays for hard-surface cleaners typically deliver upwards of 0.7ml per spraying operation, i.e. larger dosages than the sprays of the present invention. It is particularly preferred in the practice of the invention dosage is equivalent to at least 0.3ml of product delivered over an area of 80cm².

The preferred cone angles of the spray are such that 0.15-0.5ml of product is delivered over a circular region of at least 10cm diameter. The preferred droplet pattern on the surface is such that, for each pump cycle, a calculated 10-40 ml of product are delivered over each square meter of surface.

Typical cone angles in embodiments of the present invention are 25-75 degrees. Prior-used sprays for hard-surface cleaners often deliver the product in a relatively narrow cone or jet as well as delivering significantly larger quantities of product per pump cycle. As noted above, an important feature of the present invention is the reduced dosage and/or increased coverage as compared with the prior art.

The preferred droplet size distribution is such that for a 10g discharge less than 350mg of product is present in droplets having a particle size of less than 7 microns. Preferably, less than 700mg of product is present in droplets having a particle size of less than 30 microns.

Typically, the mean particle size will lie in the range 50-100 micron. It is believed that this avoids the problem of respirable particles whilst ensuring that product is delivered to the surface rather than remaining suspended in air. It is also believed that the use of this range of distribution gives good coverage of the surface and promotes the meniscus cleaning effect mentioned above.

The droplet size range for a typical product presently on the market ('CIF multiuso' (TM) trigger pack) appears to be 30-700 microns with a peak at around 250 microns.

The composition must have a viscosity such that it can be delivered in the form of spray. It is also believed essential that the composition comprises at least one nonionic surfactant. The compositions according to the present invention can be a simple solution or in a more complex form such as a microemulsion.

Particularly preferred compositions comprise 2-30% of nonionic surfactant, more preferably 3-13% nonionic. Anionic surfactant is optional. Preferred nonionic surfactants include, alkoxylated alcohols, particularly ethoxylated C8-C18 alcohols having 3-8 moles of ethylene oxide per mole of alcohol. Other nonionic surfactants may be employed, a plurality of said surfactants are disclosed in 'Nonionic Surfactants' by Schick (Arnold: surfactant science series, volume 1).

The preferred concentrations of surfactant fall into the range 5-15%wt total surfactant, with levels of around 10%wt being particular preferred. These concentrations are higher than those typically used for spray compositions, but due to the lower dosage of the composition and the improved cleaning efficiency which is seen with the practice of the present invention it is possible to reduce the overall usage of surfactant. Not only does this have a direct environmental consequence, but there is an indirect benefit in that less packaging is used for the smaller containers in which the product may be packaged and less fuel in consumed in shipping the product. There is also a direct benefit to the consumer that effective cleaning can be obtained with a light yet effective delivery device.

Hydrophobic oils are optional components of compositions according to the present invention. Suitable oils include oils which rapidly dissolve troglyceride. When oils are present preferred oils include limonene, para-cymene, dibutyl ether and butyl butyrate.

Solvents are preferably present at levels of 3-20%wt, with levels of 5-10% being particularly preferred. Glycol ether and/or lower alcohols having 1-5 carbons are preferred as solvents although the use of short alkyl chain esters including ethyl acetate and/or pyrrolidones including N-methyl pyrrolidione, is also envisaged.

Preferably, the solvent is selected from: propylene glycol mono n-butyl ether, dipropylene glycol mono n-butyl ether, propylene glycol mono t-butyl ether, dipropylene glycol mono t-butyl ether, diethylene glycol hexyl ether, methanol, ethanol, isopropyl alcohol, ethylene glycol monobutyl ether, di-ethylene glycol monobutyl ether and mixtures thereof.

Particularly preferred solvents are selected from the group comprising ethanol (preferably as industrial methylated spirits)., propylene glycol mono n-butyl ether (available as 'Dowanol PnB' [RTM]) and di-ethylene glycol monobutyl ether (available as 'Butyl Digol' [RTM] or 'Butyl Carbitol' [RTM]). These solvents are preferred due to cost, availability and safety factors. We have determined that this selection of solvents gives enhanced cleaning performance as regards inks and dyestuffs.

While the compositions of the present invention can be alkaline, acidic or neutral, it is preferred that the composition are rather strongly alkaline, having preferred pH of >10.

It is particularly preferred that the composition comprises 1-10% of an alkanolamine, with levels of 2-6%wt being particularly preferred.

Particularly suitable alkanolamines include: 2-amino-2-methyl-1-propanol, mono-ethanolamine and di-ethanolamine. These materials are believed to give improved cleaning on tough or aged soils.

We have determined that it is particularly advantageous to include a polymer in the compositions of the present invention so as to reduce the level of formation of exceptionally fine droplets, i.e. droplets which may be inhaled and cause irritation to the user. Suitable polymers include PVP, available in the marketplace as Polymer PVP K-90.

Suitable levels of PVP polymer range upwards from 50ppm. Levels of 500-1500ppm are particularly preferred.

The composition preferably has a pH of >10 and comprises, in admixture with water,:

a)	3-13%	nonionic surfactant
b)	0-10%	solvent
c)	2-6%	alkanolamine
d)	0-5%	buffer/alkali, and,
e)	50-1500ppm	polymer.

Particularly preferred compositions have a pH of >10 and comprise, in admixture with water,:

a)	3-13%	nonionic surfactant (most preferably, C10-EO5 nonionic surfactant)
b)	5-10%	solvent (most preferably, diethylene glycol mono-n-butyl ether)
c)	2-6%	alkanolamine (most preferably, 2-amino-2-methyl-1-propanol)
d)	1-5%	buffer/alkali (most preferably, sodium or potassium carbonate), and,
e)	500-1000ppm	polymer (preferably PVP),

said composition being packaged in a container adapted to produce a spray of 0.15-0.5ml of product per spraying operation, said spray having an average drop size in the range 30-300 microns.

In order that the present invention may be better understood it will be described hereinafter with reference to examples and with reference to the sole accompanying figure.

Examples

Cleaning performance was determined on soiled DECAMEL (RTM, ex. Formica) sheets. 0.5mg/cm² (based on non-volatiles) of soil were deposited on an 'A4' sized area of 'DECAMEL' test surface by spraying. The soil comprised 1% glycerol tripalmitate, 0.5% glycerol trioleate, 0.5% kaolin, 0.2% liquid paraffin, 0.1% palmitic acid, 0.02% carbon black in methylated spirits. The soil was allowed to age for 24 hours at room temperature prior to cleaning.

The effort used to remove the soil from the test surface using a cellulosic sponge cloth was measured.

Example 1

Compositions were prepared by mixing the components given in table 1 below.

10%	Imbentin 91-35 (TM) C10-EO5 nonionic surfactant,
8%	Butyl Digol (TM): diethylene glycol mono-n-butyl ether,
4%	2-amino-2-methyl-1-propanol,
2%	Buffer/alkali (sodium carbonate)
to 100%	Water

From Table 1 it can be seen that the composition is a concentrate (as regards surfactant) as compared with conventional spray cleaning compositions which comprise around 4%wt surfactant, 5% solvent.

Table 2 and figure 1 show results for six sprays using the composition described above. The compositions were sprayed onto unbaked soiled DECAMEL tiles prepared as described above using a variety of pumps. These pumps are identified in table 2 as P1-3 and C1-3. The P-series pumps were obtained from 'Perfect Valois' (TM) and the C-series pumps from 'CALMAR' (TM). The P-series pumps are identified by manufacturers codes as follows: P1: PZ2/290 4627, P2: PZ2/290 3020, P3: PZ2/290 2502. The C-series pumps are identified by manufacturers codes as follows: C1: M300 HV, C2: M300 60 degree orifice, C3: M300 30 degree orifice.

In the table and the figure, 'DS' is the mean particle concentration averaged over a five minute period from spraying, in air, of particles per cc of a diameter less than 7 microns. Higher figures for the 'DS' correspond to lower average droplet diameters in the spray.

More extensive data were obtained for pumps P1-3 and is reproduced in table 3 below. From this data, it can be seen that there is a correlation between the drop size 'DS' as measured above and the mean particle size produced by the sprays.

Returning to Table 2, cone diameter is as measured at 15cm, i.e. it is the diameter of the spray pattern at 15cm from the spray head.

The dose is the dose applied to the tiles over the area sprayed with product. In all instances more than one cycle of the spraying apparatus was used.

Effort is the total effort required to clean a tile completely, measured in terms of the total effort applied by a human operator in Ns..

From the figures given in Table 2 it is possible to calculate the dose per unit area and thus the cleaning efficiency in terms of the effort required per dose of product per unit area sprayed. Figure 1 plots this efficiency against the two series of 'drop size' (DS) measurements expressed in terms of the quantity of fine droplets. From the figure it is clearly apparent that efficiency is higher for higher values of 'DS' i.e. the same quantity of product distributed in finer drops allows the surface to the cleaned with less effort. This is true for both the 'P' series sprays and the 'C' series sprays.

Example 2

In order to demonstrate the effect of a polymer on the drop size distribution the experiments were performed with a Calmar (TM) M300 6/35 / BB034 pump actuated as a finger pump from rear. These experiments showed that in the absence of polymer the mean particle concentration averaged over a five minute period from spraying, in air, of particles per cc of a diameter less than 7 microns was 315 however in the presence of 500 ppm PVP (Polymer PVP K-90), the mean particle concentration fell to 79.

Table 4 below gives additional data for a back in which the finger-pump (all available from Calmar) were actuated by a lever.

It can be seen from table 4 that the use of a lever and an extension post further reduce the level of respirable droplets which are produced.

Example 3

In order to show directly the effect of variation in the manner in which the product is dosed, compositions were prepared by mixing the components given in table 5 below.

10%	Nonidet 91-6T (TM) C10-EO6 nonionic a surfactant
8%	Butyl Digol (TM): diethylene glycol mono-n-butyl ether
4%	2-amino-2-methyl-1-propanol
1.25%	Buffer/alkali (potassium carbonate)
1000ppm	PVP K90
0.2%	Perfume
to 100%	Water

These compositions were applied to soiled DECAMEL tiles in three ways, by means of a conventional trigger spray, by means of a pipette and at low dosage accordance with the invention. Table 6 below, provides details of the dosage (ml), effort required to clean (Ns) and cleaning efficiency (10/[ln(effort) x dose]). Efficiency was defined without reference to the spray coverage in this instance.

From the results in table 6 it can be seen that the application of the product in the low dosage characteristic of the invention gave more efficient cleaning than either the higher dosage of the conventional trigger pack, which would show some discontinuities of distribution or the particularly high dose of the pipette from which the product was dispensed as a pool. It should be noted that in these experiments the same composition was used in each instance to eliminate the possibility that the concentration of the product influenced the results.

Claims

A packaged, aqueous or solvent-containing, cleaning composition comprising a nonionic surfactant, in a container provided with a spray jet adapted to deliver the composition to a surface in the form of a spray, characterised in that the dosage applied to the surface by each operation of the spraying apparatus falls in the range 0.15-0.5ml and the said dose is applied over an area of at least 50 cm2 when the spray jet is operated 15cm from the surface.
A process for cleaning a hard surface which comprises the step of spraying a composition comprising a nonionic surfactant from a container provided with a spray jet, onto a surface in the form of a spray, characterised in that the dosage applied to the surface by each operation of the spraying apparatus falls in the range 0.15-0.5ml and the said dose is applied over an area of at least 50 cm2 when the spray jet is operated 15cm from the surface.
A process according to claim 2 wherein droplet size distribution of the product in the spray is such that for a 10g discharge less than 350mg of product is present in droplets having a particle size of less than 7 microns.
A process according to claim 2 wherein the composition comprises 1-10% of an alkanolamine.
A process according to claim 2 wherein the composition comprises a polymer.
A process according to claim 2 wherein the composition has a pH of >10.
A process according to claim 2 wherein the composition has a pH of >10 and comprises, in admixture with water,: a) 3-13% nonionic surfactant b) 0-10% solvent c) 2-6% alkanolamine d) 0-5% buffer/alkali, and, e) 50-1500ppm polymer.
A process according to claim 2 wherein composition has a pH of >10 and comprises, in admixture with water,: a) 3-13% nonionic surfactant b) 5-10% of a glycol ether solvent c) 2-6% alkanolamine d) 1-5% sodium or potassium carbonate, and, e) 500-1000ppm polymer (preferably PVP),

said composition being packaged in a container adapted to produce a spray of 0.15-0.5ml of product per spraying operation, said spray having an average drop size in the range 30-300 microns.