EP3387098A1

EP3387098A1 - Aqueous composition for cleaning hard surfaces

Info

Publication number: EP3387098A1
Application number: EP16801526.1A
Authority: EP
Inventors: Manoj Vilas Dagaonkar; Somnath Ghosh
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 2015-12-11
Filing date: 2016-11-28
Publication date: 2018-10-17
Anticipated expiration: 2036-11-28
Also published as: ZA201803602B; BR112018011710A2; PL3387098T3; EP3387098B1; EA201891392A1; BR112018011710B1; EA035067B1; WO2017097621A1

Abstract

Disclosed is an aqueous bleach-free cleaning composition comprising: (i) 1.5 to 5 % by weight surfactant system containing a. a first surfactant which is a linear alkyl benzene sulphonate; and b. a second surfactant which is an alkoxylated sulphate or a mixture of alkoxylated sulphate and up to 0.4 % by weight of non-ionic surfactant, the non-ionic surfactant having a HLB of 10 to 15; (ii) a non-phosphate alkaline builder in an amount sufficient to provide pH of 11 to 14 to said composition; and, (iii) 2 to 5 % by weight electrolyte which is a salt of a strong acid and a strong base, wherein ratio of amount of said first surfactant to that of said second surfactant is 1:1 to 1:6.5 parts by weight, wherein the second surfactant keeps the first surfactant in micellar phase, and where viscosity of said composition is 250 to 2500 cP at 20 s^-1 (0.25 Pa.s to 2.5 Pa.s) at 20°C.

Description

AQUEOUS COMPOSITION FOR CLEANING HARD SURFACES Field of the invention The invention relates to a composition for cleaning hard surfaces, more particularly for rendering toilet bowls more hygienic.

Background of the invention A variety of compositions is available for cleaning inanimate hard surfaces. Such surfaces include household surfaces such as those found inside bathrooms, toilet bowls and kitchens and are made of diverse materials such as enamel, ceramic, and porcelain. The types of stains usually encountered in lavatories, toilet bowls and bathrooms include lime scale deposits, soap scum and organic soil.

Compositions available for cleaning such hard surfaces include acidic cleaners, phenyl, bleach-based cleaners and powder compositions. Some high-end products for cleaning toilet bowls include gels and pastes.

Acidic cleaning compositions are particularly effective against lime scale. Bleach-based compositions are effective against stains. However, such compositions are harsh. Bleach has the potential to damage some of the surfaces.

WO09085049 A1 (Colgate-Palmolive) discloses a cleaning composition containing an organic acid, an ethoxylated alcohol and a hydrophilic polymer that adsorbs to hard surfaces. US2009197786 A (Reckitt Benckiser) discloses hard surface cleaning compositions particularly adapted to clean toilets. The compositions are aqueous, thickened, acidic compositions having acid, a thickening constituent, a detersive surfactant and at least one super-wetter surfactant based on a narrow range ethoxylated alcohol nonionic surfactant having two cloud points.

WO12049202A1 (Corbellini) discloses a powdery cleaning agent containing at least one acid, at least one water-soluble carbonate and at least one biocide for cleaning flush toilets and washing machines.

US6387868B (Uno Shoyu Co. Ltd, 2002) discloses clear aqueous liquid detergents containing an alkyl benzene sulfonate surfactant, liquid sodium silicate, a polyoxyethylene alkyl or aryl ether nonionic surfactant and an alkyl ether sulfate surfactant. The silicate boosts detergency. This composition is a fabric washing composition, which is dilutable and said to dissolve easily into water and not become cloudy over long period. The presence of polyoxyethylene alkyl or aryl ether nonionic surfactant and alkylethersulfate salt anionic surfactant provide stability. The pH of these compositions is about 7 to 8.

EP0379093A1 (Sterling Drug Inc, 1990) discloses highly alkaline, yet non-corrosive, aqueous hard surface cleaning compositions for cleaning industrial and kitchen surfaces soiled with burnt-on grease and other organic soils. Combination of alkanolamine to metasilicate in critical ratios along with certain other essential ingredients provide the desired technical effect.

In some parts of the world, a significant number of people still use proxy products to clean toilets. Such proxy products include low-priced detergent powders. Alternatively, some do use bleaching powders, acids, phenyls or detergent wash-liquor which is left over of fabric cleaning process. While such products do provide some degree of cleaning, they are not formulated keeping secondary uses in mind. Therefore, users of such products get sub-optimal cleaning in spite of significant efforts and inconvenience. Further, the users face the risk of exposing themselves to, or coming in contact with, organic soil such as human waste, and the wide variety of pathogenic microbes, mainly bacteria, that thrive under unhygienic conditions. In the absence of proper

communication and knowledge of appropriate consumer products, such consumers remain under the misbelief that their toilets are clean, hygienic and germ-free. Therefore, there is need for compositions, which will provide certain minimum degree of hygienic and germ-free environment within a reasonable amount of time, without the need to alter the habits of such consumers. The compositions should be bleach-free so that consumer-awareness and product literacy need not become a concern for new users. Further, such products need to be sustainable, utilising as little non-renewable resources such as synthetic surfactants, as possible. Such compositions are also required to be stable, or said in other words, there should not be phase separation, which is very likely to affect adversely the technical effect of the compositions, which is a marked reduction in bacterial count.

Summary of the invention

We have determined that solution lies in the aqueous cleaning compositions in accordance with this invention.

In accordance with a first aspect is disclosed an aqueous bleach-free cleaning composition comprising:

(i) 1.5 to 5 % by weight surfactant system containing

a. a first surfactant which is a linear alkyl benzene sulphonate; and

b. a second surfactant which is an alkoxylated sulphate or a mixture of

alkoxylated sulphate and up to 0.4 % by weight of non-ionic surfactant, the non-ionic surfactant having a HLB of 10 to 15;

(ii) a non-phosphate alkaline builder in an amount sufficient to provide pH of 11 to 14 to said composition; and,

(iii) 2 to 5 % by weight electrolyte which is a salt of a strong acid and a strong base, wherein ratio of amount of said first surfactant to that of said second surfactant is 1 :1 to 1 :6.5 parts by weight, wherein the second surfactant keeps the first surfactant in micellar phase, and where viscosity of said composition is 250 to 2500 cP at 20 s^"1 (0.25 Pa.s to 2.5 Pa.s) at 20 °C.

The invention, along with all other aspects thereof, will now be explained in details. Detailed description of the invention

The term inanimate hard surfaces includes surfaces which are particularly prone to bacterial growth such as floors, walls, tiles, sinks, shower plastified curtains, wash basins, bidets and toilet bowls of Western or Indian-style toilets.

Although the compositions in accordance with this invention are useful for toilet cleaning, the compositions may be used to clean any other inanimate hard surface and render it hygienic and germ-free.

Many people around the world face the problem of unhygienic toilets. It mostly applies to the developing and the least developed countries. Toilet bowls and the immediately adjacent area is prone to bacterial growth. Proxy cleaning products are unable to control their growth. Therefore the bacteria multiply quickly. Most bacteria which thrive under such conditions are pathogenic.

High-priced products may provide up to 5-log reduction in the viable bacterial count. However, it is an arduous task to provide such a high level of hygiene, unless the compositions contain significant amount of surfactants, bleach, antibacterial agents and other active ingredients.

Research indicates that at least 2-log reduction, i.e., 99 % reduction in viable count of bacteria, especially pathogenic ones, is necessary for minimal hygiene. It is observed that both types of bacteria, i.e., Gram-positive as well as Gram-negative bacteria thrive under unhygienic conditions. S.aureus and E.hirae are the most common Gram Positive bacteria while P. aeruginosa and E.coli are the most common Gram Negative bacteria. It is considered acceptable if a product provides 2-log reduction in at least one of each type described above. Therefore it is preferred that on contact with an inanimate hard surface comprising thereon at least one Gram positive bacteria selected from S.aureus and E.hirae and at least one Gram Negative bacteria selected from P.aeruginosa and E.coli; said

composition, provides, in accordance with BS EN 1276 protocol, at least 2-log reduction in viable count of at least one of said Gram positive bacteria and at least one of said Gram negative bacteria. Further preferably said compositions provide at least 5-log reduction. Detergent powders may provide even 1 to 2 log reduction according to European Suspension Test BS EN 1276. The EN 1276 Standard describes a Quantitative suspension test for the assessment of the bactericidal activity of chemical antiseptics and disinfectants. This test method evaluates how effectively a product causes reduction in number of viable bacterial cells of the relevant test microorganisms.

Consumers prefer aqueous hard surface cleansing products because they are easy to handle and apply. However, some of the high-end aqueous detergent products contain significant amount of surfactants and it would make little sense to use such expensive products to clean toilets. Aqueous toilet and floor cleaners need to have low solids content. Usually the acidic or bleach-based toilet cleaning products that are available in markets are stable. However, formulating a non-bleach, non-acidic aqueous hard surface cleaning composition is a technical problem, especially if the products needs to be sustainable whilst providing at least 2-log reduction in viable bacterial count.

We have determined that a solution is possible by way of a composition in accordance with the invention.

The compositions in accordance with the invention are aqueous and are bleach-free.

The term aqueous means that the compositions comprise at least 80 % by weight water. It is preferred that the compositions comprise 85 to 92 % by weight water.

By bleach-free is meant that the compositions comprise (cumulatively) less than 1 % by weight of bleaching ingredients, preferably less than 0.8, more preferably less than 0.6 and even more preferably less than 0.4 % by weight. Such ingredients include hypochlorites, sulphites, bisulphites, metabisulphites, iso-cyan urates, persulphates, percarbonates, peroxides, perborates and other bleach ingredients.

The compositions in accordance with this invention comprise 1.5 to 5 % by weight of a surfactant system. This system contains a first surfactant, which is linear alkyl benzene sulphonate (abbreviated as LAS); and a second surfactant, which is an alkoxylated sulphate or a mixture of alkoxylated sulphate and up to 0.4 % by weight of non-ionic surfactant, the non-ionic surfactant having a HLB of 10 to 15. The second surfactant keeps the first surfactant in micellar phase. The amount of surfactants, which is significantly less than conventional products, contributes to sustainability and makes the compositions in accordance with this invention less dependent on non-renewable resources.

The surfactant system:

It is preferred that the first surfactant, i.e. linear alkyi benzene sulphonate, has an alkyi chain length of Cs-2o. Generally the counter ion for anionic surfactants is an alkali metal, typically sodium, although instead of alkali metals, other amine based counter ions can also be present. Preferred linear alkyi benzene sulphonate surfactants include sodium salt of linear alkyi benzene sulphonates with an alkyi chain length of from 8 to 15, more preferably 12 to 14.

The ratio between the amount of the first surfactant to the amount of the second surfactant is from 1 :1 to 1 :6.5 parts by weight, more preferably 1 :2 to 1 :5 parts by weight. When the ratio of the surfactants is outside said range, the resulting compositions are found to be unstable, i.e. ones which are prone to phase separation. Such unstable compositions are not suited for the intended application as they are unlikely to provide at least 2-log reduction in viable bacterial count. The second surfactant is necessary to maintain the first surfactant in the micellar phase. Although not wishing to be bound by theory, repulsive forces between negative charges on the sulphonate group of the first surfactant lead to a higher critical micelle concentration (CMC) than, for instance, with a nonionic surfactant. CMC is the surfactant concentration at which micellar formation begins. Stated otherwise, the negative charge of the first surfactant inhibits micellar formation and shifts the equilibrium towards the monomer. A relatively high monomer concentration of linear alkyi benzene sulfonate in solution results in a higher packing factor, causing shift in the equilibrium from micellar to lamellar phase and thereby causing precipitation. This is significant in presence of any monovalent or divalent ions. The second surfactant is believed to prevent or at least reduce this precipitation to a significant extent. A mixed micelle forms between the first and second surfactants at lower CMC. The surfactant system therefore helps shield negative charges of the first and second surfactants from each other in the micelle. Micellar formation is, accordingly, more energetically favorable and lowers free monomer concentration.

It is particularly preferred that the second surfactant is an alkoxylated sulphate with 1 to 7 moles of alkoxylation.

The respective surfactants may be chosen from surfactants described in "Surface Active Agents" Vol. 1 , by Schwartz & Perry, Interscience 1949, Vol. 2 by Schwartz, Perry & Berch, Interscience 1958, in the current edition of "McCutcheon's Emulsifiers and

Detergents" published by Manufacturing Confectioners Company or in "Tenside- Taschenbuch", H. Stache, 2nd Edn., Carl Hauser Verlag, 1981.

Alkoxylated sulphates are anionic surfactants generally represented by the general formula RO(C2H40)_xSO3^"M⁺ where R is an alkyl chain having from 10 to 22 carbon atoms, saturated or unsaturated, M is a cation which makes the compound water- soluble, especially an alkali metal, ammonium or substituted ammonium cation, and x averages from 1 to 15. Preferably R is an alkyl chain having from 12 to 16 carbon atoms, M is sodium and x averages from 1 to 9, preferably x is 1 to 7. It is particularly preferred that the alkoxylated anionic surfactant is sodium lauryl ether sulphate (SLES). It is the sodium salt of lauryl ether sulphonic acid in which the predominantly C12 lauryl group ethoxylated with an average of 1 to 5 moles of ethylene oxide units per mole.

When a non-ionic surfactant is part of the second surfactant, the nonionic surfactant could be a primary or secondary alcohol ethoxylate, especially Cs to 2o aliphatic alcohol ethoxylated with an average of from 1 to 23 moles of ethylene oxide per mole of alcohol, prefereably 1 to 20 moles of ethylene oxide per mole of alcohol. More preferably it is C10-15 primary and secondary aliphatic alcohols ethoxylated with an average of from 1 to 10 moles of ethylene oxide per mole of alcohol. Mixtures of nonionic surfactant may also be used. It is particularly preferred that compositions in accordance with the invention comprises, individually, not more than 0.5 % by weight cationic surfactant or zwitterionic surfactant, more preferably not more than 0.3 % by weight and even more prefereably not more than 0.1 % by weight. They are avoided to prevent unfavourable interactions with other ingredients.

Builder

Compositions in accordance with this invention comprise a non-phosphate alkaline builder in an amount sufficient to provide pH of 1 1 to 14 to the composition, preferably a pH of 12 to 14. The amount of the builder will depend on its alkalinity and accordingly it will vary from builder to builder. This amount is within the knowledge of skilled persons. It is preferred that the builder is at least one of sodium hydroxide, sodium silicate, sodium disilicate or sodium aluminate.

Electrolyte

The compositions in accordance with the invention comprise 2 to 5 % by weight electrolyte which is salt of a strong acid and a strong base. The concept of strong and weak acids and bases is well known and described in basic text books on chemistry like e.g. Chapter 12.4 of Beginning Chemistry v. 1.0 (2012). It is preferred that the salt is at least one of sodium chloride, sodium nitrate, sodium sulphate, potassium chloride, potassium nitrate or potassium sulphate. It is further also preferred that the ratio between the total amount of surfactants in said surfactant system to the total amount of salt is 1 :0.3 to 1 :2.5 parts by weight.

Physical properties

Viscosity of the composition is 250 to 2500 cP at 20 s^"1 (0.25 Pa.s to 2.5 Pa.s). The viscosity is measured at 20 °C. A Haake^® AR1000 Rheometer with cone and plate assembly is used, but any equivalent machine may also be used. Use of the composition

In accordance with another aspect is disclosed an aqueous composition of the first aspect for use as an antibacterial toilet cleaner. It is preferred that the composition provides in accordance with BS EN 1276 protocol, at least 2-log reduction in viable count of at least one Gram positive bacteria selected from S.aureus and E.hirae and at least one Gram negative bacteria selected from P.aeruginosa and E.coli. It is further preferred that after application, said composition is allowed contact time of at least 15 minutes. In accordance with yet further aspect is disclosed use of a composition of the first aspect as an antibacterial toilet cleaner.

In case of using the composition for cleaning toilet bowls, the said composition can be applied to the surface and spread effectively with the help of a scrubber, left for few minutes, at least minutes, and then rinsed with water. Alternatively, the aqueous cleaning compositions of the invention may be made available to users in the form of a pre-impregnated implements like sponges.

Optional ingredients:

The aqueous cleansing compositions of the invention may optionally comprise other ingredients, such as fragrance, colorant, foam boosting agents, preservatives (e.g. bactericides), pH buffering agents, anti-oxidants, anti-corrosion agents and anti-static agents. The compositions may further comprise pearlisers and/or opacifiers.

Packaging

The composition according to the invention may be packaged in any suitable container. Preferably the compositions are packaged in a plastic bottle with a detachable closure /pouring spout. The bottle may be rigid or deformable. A deformable bottle allows the bottle to be squeezed to aid dispensing. If clear bottles are used they may be formed from PET, Polyethylene or clarified polypropylene. Preferably the container is clear enough that the liquid, with any visual cues if any, therein, is visible from the outside. The bottle may be provided with one or more labels, or with a shrink wrap sleeve which is desirably at least partially transparent, for example 50 percent of the area of the sleeve is transparent. The adhesive used for any transparent label should preferably not adversely affect the transparency.

The invention will now be described with reference to the following non-limiting examples.

Examples

Example 1 : Compositions outside the invention

Compositions outside the scope of the invention were prepared and viscosity of each composition was measured. Details of the compositions are shown in table 1.

Table 1

Note:

Na-LAS is the first surfactant

SLES 3 EO is the second surfactant

NaOH is the alkaline builder

- NaCI is the salt pH of each composition is 1 1 .5

NA - indicates not applicable

The data included in table 1 primarily indicates the effect of surfactants. When one of the surfactants is missing, the composition is either unstable or its viscosity falls significantly short of the required minimum (Example No. # 1 to 10). On the other hand, compositions 1 1 to 15 point towards the importance of ratio between the first and the second surfactant. Phase separation was observed in the case of all 'unstable' compositions'.

Example 2: Compositions inside the invention

Compositions inside the scope of the invention were prepared and viscosity of each composition was measured. Details of the compositions are shown in table 2.

Table 2

Table 2 shows that the compositions in accordance with the invention have the right viscosity. The data clearly shows the effect of the ratio. All the compositions of table 2 were stable, i.e. no phase separation. Example 3: Effect of salt

In this experiment, two similar formulations were prepared. In one formulation, 4 wt% sodium chloride was included. In the other formulation, 4 % by weight sodium acetate was included instead of sodium chloride. Viscosity of each composition was measured. Details are shown in table 3.

Table 3

The data in table 3 indicates that a salt of weak acid and strong base (sodium acetate) does not provide desired viscosity.

Example 4: Reduction in viable count of bacteria by BS EN 1276 protocol

The method is briefly described below.

The concerned test bacteria were grown overnight at 37 ^°C on a TSA (Tryptic Soya Agar) plate. The grown culture colonies were re-suspended in tryptone diluent. Density of the culture was adjusted to get final count of 1.5-5.0 x 10⁸ cfu/ml based on

McFarland standards (McFarland 1 .5 measured using bioMerieux Densomat®).

Thereafter 240 μΙ of the test solution was placed into test wells in a micro-titre plate. Equal volumes of test culture and bovine serum albumin (interfering substance) were combined for two minutes, before 60 μΙ of the mixture being added to the test solution. After a contact time of five minutes, 30 μΙ of the mixture was taken and added to a neutralising solution. This solution was then serially diluted in tryptone soya broth and then spot-plated onto TSA plates. After absorption, the plates were incubated at 37 ^°C for 24 hours and the residual colonies were counted. All the experiments were done under aseptic conditions and all media were autoclaved at 15 psi pressure before use. The extent of reduction in bacterial count was calculated by taking into account the difference between initial and final cfu/ml values.

The observations are summarised in table 4.

Table 4

Note: (i) A = E.coli, B = E. hirae, C = P. aeruginosa, D = S. aureus

(ϋ) The formulation which shows phase separation does not fall within the invention

The data in table 4 indicates that the compositions in accordance with the invention have the right viscosity and provide as much as 5-log reduction (i.e., 99.999 % reduction) in viable count of each bacteria against which the compositions were tested.

Example 5: Composition inside the scope of invention with non-ionic surfactants

Composition inside the scope of invention with non-ionic surfactants were prepared and viscosity of each composition was measured. Details of the composition are shown in table 5.

Table 5

lngredient/wt%

Total Stability/

Example Na- SLES Nl Nl Nl amount Viscosity

NaOH NaCI

No # LAS 3 EO 5EO 7EO 23EO of (cP) surfactant

24 0.7 2.8 0.1 - - 3.6 0.9 4.5 2078

25 0.7 2.8 0.2 - - 3.7 0.9 4.5 1890 26 0.7 2.8 0.3 - - 3.8 0.9 4.5 1746

27 0.7 2.8 0.4 - - 3.9 0.9 4.5 1518

28 0.7 2.8 - 0.1 - 3.6 0.9 4.5 1981

29 0.7 2.8 - - 0.1 3.6 0.9 4.5 1000

30 0.7 2.8 - - 0.2 3.7 0.9 4.5 720

31 0.7 2.8 - - 0.3 3.8 0.9 4.5 566

32 0.7 2.8 - - 0.4 3.9 0.9 4.5 347

Table 5 shows that the compositions in accordance with the invention have the right viscosity. All the compositions of table 5 were stable, i.e. no phase separation was observed.

Example 6: Compositions outside the scope of the invention with non-ionic surfactants Compositions outside the scope of the invention with non-ionic surfactants were prepared and viscosity of each composition was measured. Details of the compositions are shown in table 6.

Table 6

The data included in table 6 primarily indicates the effect of addition of non-ionic surfactant at a level that is outside the scope of invention. When the percentage of non- ionic is increased beyond 0.4 wt%, the composition is either unstable or its viscosity was falls significantly short of the required minimum.

Claims

1. An aqueous bleach-free cleaning composition comprising:

(i) 1.5 to 5 % by weight surfactant system containing

a. a first surfactant which is a linear alkyl benzene sulphonate; and b. a second surfactant which is an alkoxylated sulphate or a mixture of alkoxylated sulphate and up to 0.4 % by weight of non-ionic surfactant, the non-ionic surfactant having a H LB of 10 to 15;

(ii) a non-phosphate alkaline builder in an amount sufficient to provide pH of 1 1 to 14 to said composition; and,

(iii) 2 to 5 % by weight electrolyte which is a salt of a strong acid and a strong base,

wherein ratio of amount of said first surfactant to that of said second surfactant is 1 :1 to 1 :6.5 parts by weight, wherein the second surfactant keeps the first surfactant in micellar phase, and where viscosity of said composition is 250 to 2500 cP at 20 s^" ¹ (0.25 Pa.s to 2.5 Pa.s) at 20 °C.

2. An aqueous composition as claimed in claim 1 wherein said builder is at least one of sodium hydroxide, sodium silicate, sodium disilicate or sodium aluminate.

3. An aqueous composition as claimed in claim 1 or 2 wherein said salt is at least one of sodium chloride, sodium nitrate, sodium sulphate, potassium chloride, potassium nitrate or potassium sulphate.

4. An aqueous composition as claimed in any one of claims 1 to 3 wherein said

composition comprises not more than 0.5 % by weight of any one of a cationic surfactant or a zwitterionic surfactant.

5. An aqueous composition as claimed in any one of claims 1 to 4 wherein said

composition comprises not more than 0.3, preferably not more than 0.1 % by weight of any one of a cationic surfactant or a zwitterionic surfactant.

6. An aqueous composition as claimed in any one of claims 1 to 5 wherein on contact with an inanimate hard surface comprising thereon at least one Gram positive bacteria selected from S. aureus and E.hirae and at least one Gram Negative bacteria selected from P. aeruginosa and E.coli; said composition, provides, in accordance with BS EN 1276 protocol, at least 2-log reduction in viable count of at least one of said Gram positive bacteria and at least one of said Gram negative bacteria.

7. Use of a composition as claimed in any one of claims 1 to 5 as an antibacterial toilet cleaner.