FORM - 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)
AQUEOUS LIQUID BLEACH COMPOSITIONS
HINDUSTAN UNILEVER LIMITED, a company incorporated under the Indian Companies Act, 1913 and having its registered office at Hindustan Lever House, 165/166, Backbay Reclamation, Mumbai -400 020, Maharashtra, India
The following specification particularly describes the invention and the manner in which it is to be performed

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AQUEOUS LIQUID BLEACH COMPOSITIONS
Technical field
The present invention relates to aqueous thickened liquid bleach and disinfectant compositions comprising
hypochlorite, quaternary ammonium halogenide surfactant and a thickening system. The invention also relates to the use of such compositions for cleaning and disinfecting hard surfaces.
Background and prior art
Aqueous liquid hypochlorite bleach compositions are well known in the art. On the one hand they are used for bleaching and stain removal on laundry, on the other hand
they are used for cleaning and disinfecting hard surfaces such as kitchen surfaces, floors and in particular toilets. To increase contact time between the surface and the bleach, on inclined and vertical surfaces bleach compositions intended for cleaning hard surfaces- preferably have a
relatively high viscosity and such. compositions are generally known as "thick bleach".
Various thickening systems for hypochlorite have been described in the prior art involving a large variety of
combinations of surfactants. Among these GB 1,466,560
describes-thickening systems comprising an alkali metal
- sarcosinate or tauride surfactant and another surfactant
chosen from amine oxides, quaternary ammonium compounds,
betaines, alkanolamides and fatty acid soaps. From this
latter list only combinations involving an amine oxide or a

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soap are exemplified. EP 298172, US 5,055,219 and US 5,336,426 all disclose thickening mixtures comprising a quaternary ammonium compound and an organic counter ion which may be a C1-C10 alkyl or aromatic sulphonate or sulphate or aliphatic or aromatic carboxylate.
Although active chlorine compounds, and particularly hypochlorite, are known to be powerful disinfectants for hard surfaces, this disinfectant activity is short-lived,
i.e. after a surface has been treated with an active chlorine compound it can quickly become microbially recontaminated again. This is particularly true if the surface is rinsed with water after the treatment, because this washes away any traces of active chlorine compound left
on the surface.
In US 2,987,435 it is disclosed that quaternary ammonium salts are effective antimicrobial compounds. Treating a surface with a combination of hypochlorite and a quaternary
ammonium salt leaves antimicrobial activity on the surface even after rinsing with water. The compositions typically contain 0.5-1% active chlorine. More concentrated compositions were said to lead to phase separation such as emulsions or precipitates. The compositions are particularly
suitable for treating textiles and fibres and are therefore preferably thin liquids.
EP 844827 discloses that aqueous compositions comprising up to 0.25% active chlorine compound and up; to 0.08% bactericidal quaternary ammonium compound are able to kill tubercule bacilli on hard surfaces. Preferred quaternary

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ammonium compounds are the di(C8-C12)alkyl-dimethylammonium salts and the (C12-C18)alkyl-dimethyl-benzylammonium salts Didecyl-dimethylammonium chloride and (C12-C16)alkyl-dimethyl-benzylammonium chloride are specifically mentioned. It is said to be advisable to keep the active chlorine
solution and the quaternary ammonium salt solution separate until the moment of use to prevent the active chlorine solution to lose part of its active chlorine content.
Indeed it has been found by experimentation that in the long term most quaternary ammonium compounds' are not stable in hypochlorite solution and that such solutions after weeks of storage tend to lose a significant part of the active chlorine as well as of the quaternary ammonium content. In
those cases where the quaternary ammonium compounds were stable many were found to adversely interfere with the thickening system of the hypochlorite bleach, leading in many cases to unacceptable loss of viscosity and in some cases to excessive thickening causing the formation of thick
gels which were impossible to be dispensed by pouring.
Desirable methods for oxidative cleaning/bleaching of any
surface should provide powerful initial disinfectancy as
well as give sufficient residual antimicrobial activity on a
surface to prevent bacterial regrowth for extended periods
of time, also after rinsing with water. Compositions
suitable for use in such methods should be sufficiently
stable to be manufactured, shipped and stored, on the shelf as well as f by ft he consumer, without appreciable loss of
active chlorine. Furthermore such compositions should :have a suitable viscosity to cling on inclined or vertical

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surfaces, such as found in toilets and bathrooms and yet be able to be dispensed easily.
Summary o£ the invention
It has now been found that treatment of surfaces with a liquid composition comprising a combination of hypochlorite and one or more specific quaternary ammonium chlorides provides thorough oxidative cleaning and removal of stains
while at the same time not only disinfecting the surface,
but providing antimicrobial activity on the cleaned surface for an extended period of time. By selecting specific quaternary ammonium salts compositions are provided that can be stored for long periods of time without appreciable loss
of active chlorine or quaternary ammonium compound and that have the suitable viscosity to be used as "thick bleach" .
Thus, the invention provides thick liquid hypochlorite bleach compositions comprising one or more inorganic quaternary ammonium salts and a suitable thickening system comprising amine oxide surfactant and fatty acid.
Furthermore, the invention provides a method of cleaning and disinfecting hard surfaces, particularly inclined or vertical surfaces such as found in toilets and bathrooms comprising applying to the surface a liquid bleaching composition comprising hypochlorite and one or more specific quaternary ammonium halides and a thickening system . comprising amine oxide surfactant and fatty acid;

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Detailed description of the invention
All percentages mentioned herein are by weight based on the total composition, unless specified otherwise.
Accordingly, the invention provides aqueous liquid bleaching compositions comprising a hypochlorite salt and a quaternary ammonium salt characterised in that the ammonium salt has the general formula: RiR2R3R4N+ X", wherein Rx is a C12-C18 alkyl group, each of R2, R3 and R4 independently is a C].-C3 10 alkyl group and X is an inorganic anion and the composition comprises a thickening system comprised of amine oxide surfactant and fatty acid.
The hypochlorite salt is generally an alkali metal or alkaline earth metal salt although other salts may be used. The Na and Ca salts are most widely used. The compositions used for the purposes of the invention generally comprise 0.01-10% Nalco or an equivalent amount of other hypochlorite salt, which is equivalent to about 0.0095-9.5% available chlorine and to 0.0014-1.4 mol/1 of hypochlorite ion.
Preferably the hypochlorite ion content is 0.005-1.0 mol/1, more preferably at least 0.01 mol/1, most preferably at least 0.05 mol/1 or even 0.1 mol/1.
In the quaternary ammonium salts according to the present invention R1 is preferably a C14-C16 straight chain alkyl group, more preferably C16. R2-R4 are preferably methyl groups. The inorganic anion is preferably chosen from halide, sulphate, bisulphate or OH". Thus, for =t-he purposes
of this invention:, a quaternary ammonium hydroxide is C
considered to be a quaternary ammonium salt. More preferably

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the anion is a halide ion or sulphate, most preferably a chloride or sulphate. Cetyl-trimethylammonium chloride is a specific example of a suitable compound and commercially abundantly available.
In general the quaternary ammonium salts suitable for the invention are preferably stable enough to hypochlorite to have at least 60% of the original amount of available chlorine left after 4 weeks storage at 20°C, i.e. 2.9 wt% available chlorine starting from 4.8%wt in the fresh
composition (Example formulation 1 below). More preferably at least 70% of the original amount available chlorine is left after the 4 weeks storage test.
The compositions according to, and used in the methods of the invention generally comprise 0.001-0.5 mol/1 of the quaternary ammonium ion, preferably 0.005-0.1 mol/1, more preferably at least 0.01 mol/1. The molar ratio between hypochlorite ion and quaternary ammonium ion is usefully
kept between 500:1 and 1:1, preferably between 200:1 and 2:1. Even more useful ratios are at or below 100:1. The halide ion is preferably chloride or bromide, more preferably chloride.
Suitable amine oxide surfactants for use in the thickening system are tertiary amine oxides of structure RRRNO, where one R is an alkyl group of 8 to 20 carbon atoms and the other ; R’s are each alkyl or hydroxyalkyl groups of 1 to 3 carbon t atoms, preferably methyl groups. The large alkyl group preferably has at least 12, more preferably at least 14
carbon atoms. The amine oxide is preferably used in an amount

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of at least 0.02%, more preferably at least 0.05%, most preferably 0.1 or even 0.5%, but preferably not above 10%, more preferably 5%. Fatty acids are aliphatic carboxylic acids and suitable fatty acids have 8-20 carbon atoms, preferably in a straight chain. Preferred acids are those having a C10-C18 alkyl group, more preferred those having an alkyl group of at least 11 C-atoms. The fatty acids are preferably used in an amount of at least 0.05%, more preferably 0.1%, but preferably not above 5%, more preferably 2%.
For long-term stability the compositions used for the purposes of the invention need to be alkaline, i.e. have pH above 7. Preferably the pH is kept at or above 8, more preferably at least 9 or even 10.
The compositions according to the invention are particularly suitable to be used as is, i.e. without prior dilution. In order to be conveniently dispensed from suitable containers whilst also clinging to inclined surfaces they preferably
have a viscosity of 20-5000mPa.s, preferably 100-2000 mPa.s, more preferably 200-1000 mPa.s (measured with a Haake RT20 Rotovisco rheometer fitted with a coaxial cylinder sensor DIN 53018 (Z41 rotor and Z43 measuring cylinder), using a 3 25 mm gap. Flow curves were obtained at 25° C over the shear rate range 0.1 to 1000 s"1) .
Whilst the pure compositions may not be suitable to come into contact" with the human.- skin on account of their, high , content of hypochlorite, they can be applied to a .surface manually (e.g. with a wipe or cloth or other implement)

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after proper dilution. Suitable dilution factors are generally between 1:5 and 1:500
As outlined above, compositions according to the invention, either dilute, but preferably pure are applied to the surface to be treated and are left in contact with that . surface for a sufficiently long time to oxidatively clean and disinfect that surface, whereafter the surface may be rinsed if desired. Generally, contact times of 1 minute are
sufficient for initial disinfectancy, with contact times of at least 5 minutes being used to obtain long term disinfectancy, preferably at least 15 minutes, more preferably at least 30 minutes. One example of such embodiment involves applying a composition according to the
invention with a spraying device such as a trigger spray or similar as well known in the art of hard surface cleaning. Another embodiment of the invention involves applying a squirt of the product according to the invention straight from the container in which it is provided to the surface to be treated.
The invention particularly provides a method for cleaning and disinfecting toilet surfaces comprising applying to the surface a composition as described above. In a preferred
embodiment, wherein the toilet surface to be treated is the toilet bowl, a composition as described above is applied directly from the container to the bowl, either above the water table to the surface of the bowl e.g. under the rim', or to the water in the bowl. Particularly suitable ."-
containers for that purpose are well known in the art.
Typically for such containers the longitudinal axis of the

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dispensing opening in the cap makes an angle of generally less than 90° (preferably 10-80°) with the longitudinal axis of the bottle to enable easy application of the composition under the rim of the toilet bowl. An example of such a bottle is depicted in the UK Industrial Design registration no. 1057823. Applying the concentrated composition to the water in the bowl will generate a diluted solution according to the invention.
As outlined above, treating a surface with a bleaching composition according to the invention will not only oxidatively clean and disinfect that surface, but also provides extended antimicrobial activity on that surface such that regrowth of micro-organisms is prevented for many hours after the treatment is completed, particularly if the composition is left to dry out on the surface. The antimicrobial activity remains after rinsing, even repeated rinsing, of the surface, in spite of the fact that the hypochlorite and quaternary ammonium salt in the composition are soluble in water and would be expected to be rinsed away.
The compositions according to the invention can optionally contain many other components known in the art to be useful in bleach compositions. The high viscosity cause the composition to slowly flow down the surface, thus providing prolonged contact time between the composition and the surface leading to improved cleaning and disinfection, and without any manual intervention.-

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Other optional components include builders, antioxidants, radical scavengers, chelating agents for metals prone to induce or accelerate hypochlorite decomposition such as silicates or periodates, hydrotropes, anticorrosion agents. Solid abrasives may be added as well.
Further hypochlorite stable surfactants may be added to improve cleaning properties, provided they do not adversely affect the properties of the thickening system.
Colorants, dyes and pigments may be added to impart a desired colour to the compositions and perfumes to give the compositions a desired odour, particularly to overcome the hypochlorite odour which many people do not appreciate. The components should chosen to be bleach-stable, as is well known in the art.
As outlined above, the compositions according to the invention are alkaline and sufficient alkali, preferably alkalimetal hydroxide, should be present to ensure this. The compositions could also usefully contain buffer to ensure long term pH stability. .Alkali metal carbonates/bicarbonates and silicates are particularly useful for that purpose.
Examples
Aqueous liquid bleaching compositions were prepared according to the formulations 1-4 in Table 1 below (amounts in %) :

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Table 1

1 2 3 4
Na hypochlorite 4.80 4.80 4.80 4.80
Cetyl-trimethylamm. chloride 0.50 0.50 1.00 1.00
Empigen OD * 1.25 0.75 0.75 0.75
Laurie acid 0.30 0.30 0.20 0.10
Perfume 0.06 0.06 0.06 0.06
Alkaline Na silicate 0.05 0.05 0.05 0.05
Viscosity, mPas (at 1-3 s"1) 455 545 800 170
Viscosity, mPas (at 21 s"1) 360 390 480 140
All examples sufficient NaOH to pH 12.5. All examples demin water to 100% *) C10-C18 alkyl-dimethylamine oxide marketed by Huntsman
Viscosity measurements
Formulation viscosities were measured using a Haake RT20 Rotovisco rheometer fitted with a coaxial cylinder sensor DIN 53018 (Z41 rotor and Z43 measuring cylinder), using a 3 mm gap. Flow curves were obtained at 25° C over the shear rate range 0.1 to 1000 s"1.
Comparative tests;
The viscosity appearance, long lasting hygiene score and hypochlorite stability of Formulation 1 above and of compositions comprising hypochlorite and various other quaternary ammonium salts was determined and the results are presented below in Table 2. For the quaternary ammonium salts; -0-.5% of each compound was-. added instead of cetyl- ; _. - trimethyl-ammonium chloride to a formulation according to Formulation 1.

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Viscosity was measured and appearance assessed immediately after preparation and after 1 week storage at ambient temperature.
The absolute residual hypochlorite content was determined after 1 and 4 weeks in the dark at ambient temperature. The results are presented in Table 2 below.

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Table 2

Quaternaryammoniumsalt Appearanceafterprep. Appearance after 1 week Hyg. * score: Av.Cl 1 wk ** Av.Cl 4 wks **
Cetyl-trimethyl-amm. Cl Standard viscosity Standard viscosity 15 4.1
Cetyl-trimethyl- . amm. Br Increased viscosity Increased viscosity 11 3.8 2.7
Tetradecyl-trimethyl-amm. Cl Increased viscosity Increased viscosity 5 3,5
Dodecyl-pyridiniumCl Reduced viscosity Very low viscosity 0 1.9 0.7
Cetyl-pyridiniumCl Increased viscosity granular gel Very low viscosity, particle separation 0 1.9 0.5
Benzalkonium Cl Reduced viscosity Very low viscosity 15 3.9 2.9
Tetrabutyl-amm. Cl Very low viscosity Very low viscosity 13 0.4 —
Tetraheptyl-amm. Cl Very low viscosity Very low viscosity, particle separation 15 3.7 3.3
l,3-Decyl-2-methyl-imidazolium Cl Very low viscosity Very low viscosity 11 1,6 0.8
1-Hexadecyl-3-methyl-imidazolium Cl Increased viscosity Very low viscosity Particle separation 0 1.9 0.3
Didecyl-dimethyl-amm. Br Very low viscosity Very low viscosity 13 3.6 2.9
Didecyl-dimethyl-amm. Cl Reduced viscosity Very,lowviscosityseparation 15 3,5. 2, 4;

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* Hygiene score expressed .as the number of rinses that a
microtitre plate well remained bacteria-free.
** Expressed as available chlorine in wt% after 1 and 4
weeks storage at 20°C respectively, starting from 4.8% Na hypochlorite.
Chlorine determination
The residual available chlorine present was analysed iodometrically, using the following procedure: A known weight of the test solution (w) was placed in an iodine flask. The sample was diluted with approximately 2 0 ml distilled water. 10 g of 5% potassium iodide solution was added followed by 10 ml of 0.5 M sulphuric acid. The flask was- stoppered and swirled to. mix the contents before placing in dark for 5 minutes, until the brown colour of the evolved iodine had fully developed. The liberated iodine was titrated against 0.1 M sodium thiosulphate solution until the solution becomes colourless, with additional of soluble starch indicator near the end point to aid accuracy.
Hygiene score test
The test uses a high throughput screening method to assess
the hygienic properties of standard samples of 10ml of
product dispensed in microtitre plate wells that have been left to dry (at 30°C overnight) and are thereafter subjected to a number of automatic rinses. Each test is done in 8 replicates. The rinses were done with a Ascent Wellwash™
opiate wisher with sterile water of standard hardness, After a set number of rinses the plates were dried at 30°C for 45 minutes and left to cool at 20°C for 15 minutes. Each well

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was thereafter incubated with 50ml of an aqueous suspension of E.coli (0.5x108 cfu) in 0.3% protein (BSA) soil and left in contact for lh at 20°C. The wells were then washed by-adding 100ml water of standard hardness and shaking for lOsec, whereafter the wash liquour and unattached cells were aspirated off.
Thereafter 270m1 of tryptone soya broth growth medium is placed in each well and the plates are incubated for 24h at 37°C to allow remaining bacteria to re-grow. A test is classified as successful after the set number of rinses if at least 80% of the samples show no regrowth. The highest number of rinses that lead to a successful test is taken as the hygiene score.

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CLAIMS
1. Aqueous liquid bleaching compositions comprising a hypochlorite salt and a quaternary ammonium salt characterised in that the ammonium salt has the general formula: RiR2R3R4N+ X", wherein R1 is a C10-C20 alkyl group,, each of R2, R3 and R4 independently is a C1-C3 alkyl group and X is an inorganic anion and the composition comprises a thickening system comprised of amine oxide surfactant and fatty acid.
2. Aqueous liquid bleaching compositions according to claim 1 characterized in that they comprise at least 0.01 mol/1 hypochlorite ion.
3. Aqueous liquid bleaching compositions according to claims 1 or 2 characterized in that Rx is a C14-C16 straight chain alkyl group and R2-R4 are methyl groups.
4. Aqueous liquid bleaching compositions according to claims 1-3 characterized in that they comprise 0.001-0.5 mol/1 quaternary ammonium ion.
5. Aqueous liquid bleaching compositions according to claim 4 characterised in that they comprise at least 0.01 mol/1 quaternary ammonium ion.
6. Aqueous, liquid bleaching compositions according to claims 1-5 characterized in "that the molar ratio of hypochlorite in, to quaternary ammonium ion is between 500:1 and 1:1

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7. Aqueous liquid bleaching compositions according to claim 6 characterized in that the molar ratio of hypochlorite ion to quaternary ammonium ion is at or below-100:1.
8. Aqueous liquid bleaching compositions according to any one of claims 1-7 characterized in that the quaternary ammonium salt is a halide.
9. Aqueous liquid bleaching compositions according to claims 1-8 characterized in that the amine oxide surfactant is an tertiary amine oxide of structure RRRN0, where one R is an alkyl group of 8 to 20 carbon atoms and the other R's are each alkyl or hydroxyalkyl groups of 1 to 3 carbon atoms and the fatty acid has 8-20 carbon atoms.
10. Aqueous liquid bleaching compositions according to claim 9 characterized in that they comprise 0.05-10% amine oxide and 0.05-5% fatty acid.
11. Aqueous liquid bleaching compositions according to claims 1-10 characterized in that they have a viscosity of 20-5000 mPa.s.
12. A method for providing lasting antimicrobial activity on a hard surface comprising treating that hard surface with a .composition according to any one of claims 1-11.

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13. A method according to claim 12 characterized in that the surface is thereafter rinsed with water.
14. A method according to claim 12 characterized in that the surface is a toilet surface.
15. A method according to claim 13 characterized in that the toilet surface is the surface of the toilet bowl.
16. A container comprising a bottle and a cap with a dispensing opening, and a bleaching composition contained in the container, characterized in that the longitudinal axis of the dispensing opening makes an angle of less than 90° with the longitudinal axis of the bottle and the bleaching composition inside the container is a composition according to claims 1-11.