Perfumed acidic hard surface cleaning composition

Abstract

The present invention relates to aqueous acidic cleaning compositions for acid-resistant hard 5 surfaces. The invention addresses the need for compositions in which standard perfume or fragrance ingredients are stabilised for longer duration in highly acidic medium and is released upon dilution with water without necessarily needing any shear force. Disclosed is an aqueous composition for cleaning acid-resistant hard surfaces, said composition 0 comprising: a) an acid of sufficiently high dissociation constant [Ka] in an amount such that pH of said composition is from 1 to 3; and, b) particulate pH-responsive encapsulates comprising perfume encapsulated in an encapsulating material which is acid-stable upto pH 3 and is capable of disintegrating to release said perfume 5 at pH beyond 3, where said encapsulates are present in an amount such that said composition comprises 0.1 to 5 wt% of said perfume, wherein, said encapsulating material comprises a polymer having zeta potential of -30 mV to -80 mV. 0

Description

[0001] Perfumed acidic hard surface cleaning composition

[0002] Field of the Invention

[0003] The present invention relates to aqueous acidic cleaning compositions for acid-resistant hard surfaces.

[0004] Background of the invention

[0005] A variety of cleaning compositions are known for use on acid-resistant hard surfaces such as toilet bowls, bathroom tiles, commodes, and certain kinds of flooring. Such compositions generally contain an acidic component, usually a strong mineral acid, a dye, and fragrance that are flushed with water to produce their desired cleaning, disinfecting, and deodorising effects. Acidic compositions are effective at removal of stubborn soil including organic stains, limescale deposit, and discoloration.

[0006] Usually, the pH of such compositions is from 0 to 3 as they contain strong mineral acids, such as hydrochloric acid or sometimes other acids such as trichloroacetic acid, trifluoroacetic acid, perchloric acid, sulphamic acid and phosphoric acid. However, hydrochloric acid is preferred due to cost and availability. In use, the composition is directly applied to the acid-resistant surface and left in contact therewith generally for 15 to 20 minutes after which the surface is rinsed with water. When a large quantity of water is poured over the surface, the pH of the composition that has been applied on the surface increases up to 6 to 6.5 due to almost an infinite dilution of the cleansing composition. Certain compositions contain pH-responsive dyes for a visual appeal.

[0007] US2013042887 Al (Avery Richard) discloses toilet cleaning compositions comprising an inorganic or organic acid. The pH of the compositions is not more than 4. The compositions contain fragrance.

[0008] CN104004598 A (Chen Jianbao) discloses aqueous toilet cleaning composition comprising 13 to 19 wt% HC1, 7.5 to 8 wt% STPP and 0.8 to 1.2 wt % fragrance.

[0009] US7470331 Bl (Clorox) discloses a cleaning composition comprising alkyl polyglucoside, a 2- hydroxylcarboxylic acid, and fragrance containing lemon oil or d-limonene. The cleaning composition is used to clean hard surfaces and is said to clean as well or better than commercial compositions containing synthetic cleaning agents. US2023416642 Al (P&G) discloses isotropic aqueous compositions with pH 1 to 6 comprising a surfactant system which includes alkyl polyglucoside and ethoxylated alcohol and a high level of perfume. The composition also contains an acid. The composition contains organic and / or an inorganic acid having pKa less than 6. As organic acids, citric acid, lactic acid, formic acid, glycolic acid, succinic acid, glutaric acid and adipic acid are preferred whereas hydrochloric acid, sulphuric acid, phosphoric acid are the preferred inorganic acids.

[0010] US2013247936 Al (Colgate) discloses an aqueous bathroom or kitchen cleaning composition comprising lactic acid and phosphoric acid at weight ratio of 1:3 to 3: 1, nonionic ethoxylated alcohol, anti-adhesion polymer comprising a polybetaine and thickener chosen from xanthan gum, gellan gum, carrageenan gum, hydroxyethyl cellulose, and a perfume. The pH is from 1 to 3.

[0011] While acidic cleaning composition often contain perfume ingredients, most of the standard fragrances are unstable in the acidic medium. Due to such instability, the user may get exposed to strong acidic odour at the time of use rather than a pleasant fragrant aroma. The acids in such compositions may produce vapours in the containers in which they are stored and whenever such compositions are dispensed, the acidic odour predominates even if a fragrance is present.

[0012] A solution is disclosed in US6248705 Bl (P&G) in which the stable, perfumed, highly acidic liquid composition for toilet bowls contains a source of active oxygen, a surfactant and a cyclic terpene / sesquiterpene compound (e.g. eucalyptol). The cyclic terpene / sesquiterpene perfume is insensitive to acidic pH. By incorporating such perfume into the highly acidic liquid composition the perfume remains stable for longer period.

[0013] Another solution is disclosed in W02008028310 Al (Givaudan) in which the cleaning composition comprises a strong acid, an oily material and at least one electrolyte. The oily material has a maximum viscosity of 100 cSt at 20 °C and comprises an oil-soluble fragrance due to which the strong and often potentially hazardous odour generally characteristic of such cleaners is eliminated or substantially reduced. The oily material is a liquid hydrocarbon, or any organic liquid having the characteristics of an oil (such as liquid silicones).

[0014] There are some pH-responsive materials that are stable within a defined range of pH and which disintegrate outside the defined range of pH, usually at a higher pH. US2020237629 Al (Colgate) discloses a composition comprising pH-sensitive microcapsules comprising a shell wall having a polymer chosen from cellulose derivatives and acrylate derivatives, and at least one structuring agent chosen from shellac, ethyl cellulose, and fumed silica. A functional ingredient such as a perfume is encapsulated in the shell wall. The microcapsules are added to a carrier having acidic pH. The pH-sensitive microcapsule disintegrates during use of the composition and releases the perfume into the carrier. The disintegration may be achieved through mechanical means as well.

[0015] In the publication titled Mater. Res. Express 7 (2020) 082001, the authors Wei. et., al have described various polymers to control the release pattern of fragrance by encapsulation or loading it with a substrate material. Responsive fragrance release systems with specific stimuli responsiveness can be designed based on the kind of response that would serve as a stimulus, for example, mechanical, chemical, thermal and light responsive fragrance release systems. The publication discloses shellac as natural ester suitable for encapsulating fragrances in a pH- responsive manner.

[0016] In Particuology 26 (2016) 40 to 46, the authors Long et.al have described calcium shellac (CS) matrix to encapsulate polymeric melamine formaldehyde microcapsules (A) or CaCCh nanoparticles-stabilized microcapsules (B), both of which encapsulate an oil-based active ingredient, producing A-CS or B-CS composite microcapsules. The mechanical properties and oil release profdes of the composite microcapsules are evaluated. The composite microcapsules showed enhanced mechanical stability and reduced leakage of the active ingredient by one order of magnitude.

[0017] The composite microcapsules of CS containing MF microcapsules (A-CS) or CaCCh nanoparticle microcapsules (B-CS) are prepared as follows.

[0018] One gram of MF microcapsules (A) or CaCO3 nanoparticle-stabilized microcapsules (B) is dispersed in an aqueous solution of shellac ammonium salt (5 m ). Sunflower oil (200 mb) is added to the resulting dispersion and the mixture is stirred using a homogenizer. Calcium chloride is added every minute over ten minutes (1 g in total) to the resulting emulsion, and stirring is maintained for another 2 hours. The Ca+2migrate to the oil-water interface and ion exchange with NHC and the carboxylate anions, resulting in cross-linking of the shellac wall. The resulting composite capsules (A-CS and B-CS) are isolated from sunflower oil by fdtration and dried using a freeze dryer. CS microparticles are prepared by adding 200 ml sunflower oil to the aqueous solution of shellac ammonium salt (5 mL), and the resulting mixture is emulsified using a homogenizer. Thereafter, calcium chloride (0.1 g) is added every minute over 10 minutes (1 g in total) to the emulsion, and the stirring is maintained for another two hours. The resulting microparticles are isolated from sunflower oil by filtration and, freeze dried.

[0019] On the other hand, in Food Hydrocolloids, Volume 100, March 2020, 105377 Muhammad et.al., have described preparation of stable shellac nanoparticles containing a cinnamon bark extract using xanthan gum by anti-solvent precipitation. Shellac is said to be restricted in its application as a delivery system for bioactive compounds due to its tendency to aggregate at acidic pH. As shellac tends to aggregate at acidic pH, xanthan gum is incorporated into the anti-solvent phase to stabilise the system and prevent aggregation.

[0020] Despite a variety of prior art in the field of perfumed aqueous acidic cleaning compositions, there is need for compositions in which standard perfume or fragrance ingredients could be stabilised longer in highly acidic medium and which can be released upon dilution with water without necessarily needing any shear force.

[0021] Summary of the invention

[0022] The present inventors have surprisingly determined that a standard perfume or a fragrance can be stabilised for longer duration in an acidic aqueous composition for cleaning acid-resistant hard surfaces and the perfume is capable of release upon dilution with water without necessarily needing any shearing force to give the user a pleasant olfactory experience. The aqueous composition of the invention comprises: a) an acid of sufficiently high dissociation constant [Ka] in an amount such that pH of the composition is from 1 to 3; and, b) particulate pH-responsive encapsulates comprising perfume encapsulated in an encapsulating material which is acid-stable upto pH 3 and is capable of disintegrating to release said perfume at pH beyond 3, where said encapsulates are present in an amount such that said composition comprises 0.1 to 5 wt% of said perfume.

[0023] The technical effect has been observed when the encapsulating material comprises a polymer having zeta potential of -30 mV to -80 mV. Without wishing to be bound by theory it is believed the zeta potential of the polymer, stabilises the perfume for longer duration not just in packaged condition, but also ensures prolonged and sustained release of the perfume at the time of use on an acid-stable surface.

[0024] In accordance with the invention disclosed is an aqueous composition for cleaning acid-resistant hard surfaces, said composition comprising: a) an acid of sufficiently high dissociation constant [Ka] in an amount such that pH of said composition is from 1 to 3; and, b) particulate pH-responsive encapsulates comprising perfume encapsulated in an encapsulating material which is acid-stable upto pH 3 and is capable of disintegrating to release said perfume at pH beyond 3, where said encapsulates are present in an amount such that said composition comprises 0.1 to 5 wt% of said perfume, wherein, said encapsulating material comprises a polymer having zeta potential of -30 mV to -80 mV. Preferably the encapsulating material and the polymer having zeta potential of -30 mV to -80 mV are not identical.

[0025] In accordance with a second aspect disclosed is a method of cleaning acid-resistant hard surfaces comprising the steps of: i) applying thereto an aqueous composition for cleaning acid-resistant hard surfaces of the first aspect; ii) allowing for a contact time of 5 to 30 minutes; and iii) rinsing said surface with water, wherein said method provides at least 99% or 2-log germ kill of microbes present on said hard surface.

[0026] Preferably the contact time is 10 to 20 minutes. Preferably the acid-resistant hard surface is of a kitchen worktop, kitchen floor, sink, kitchen counter-top, floor, bathroom tile, toilet bowl or a commode.

[0027] Detailed description of the invention

[0028] These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from a reading of the following detailed description and the appended claims. For the avoidance of doubt, any feature of one aspect of the present invention may be utilized in any other aspect of the invention. The word “comprising” is intended to mean “including” but not necessarily “consisting of’ or “composed of.” In other words, the listed steps or options need not be exhaustive. It is noted that the examples given in the description below are intended to clarify the invention and are not intended to limit the invention to those examples per se. Similarly, all percentages are weight / weight percentages unless otherwise indicated. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description and claims indicating amounts of material or conditions of reaction, physical properties of materials and / or use are to be understood as modified by the word “about”. Numerical ranges expressed in the format “from x to y” are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format “from x to y”, it is understood that all ranges combining the different endpoints are also contemplated. In other words, in specifying any ranges of values, any particular upper value can be associated with any particular lower value.

[0029] The invention relates to an aqueous composition for cleaning acid-resistant hard surfaces. The term acid-resistant hard surface means and includes surfaces such as enamel and porcelain which can tolerate contact with strong acids without undergoing deterioration or etching. Acid-resistant may also be interpreted to mean acid stable.

[0030] The term hard surface includes kitchen worktops, kitchen floors, sink, kitchen countertops, floors, bathroom tiles, toilet bowls and commodes. It is preferred that the composition is used to clean hard surfaces that are amenable to be cleaned by strong acids. Therefore, more preferably the composition of the invention is used to clean acid-resistant hard surfaces such as bathroom tiles, toilet bowls, commodes or any soiled hard surfaces.

[0031] The composition

[0032] The aqueous composition of the invention is suitable for cleaning acid-resistant hard surfaces.

[0033] The composition comprises: a) an acid of sufficiently high dissociation constant [Ka] in an amount such that pH of said composition is from 1 to 3; and, b) particulate pH-responsive encapsulates comprising perfume encapsulated in an encapsulating material which is acid-stable upto pH 3 and is capable of disintegrating to release said perfume at pH beyond 3, where said encapsulates are present in an amount such that said composition comprises 0. 1 to 5 wt% of said perfume, wherein, said encapsulating material comprises a polymer having zeta potential of -30 mV to -80 mV. Aqueous means that the composition comprises water as a carrier. Preferably the composition of the invention comprises 65 to 90 wt% water. More preferably the composition comprises 75 to 90 wt% water. Preferably the water is deionised. Alternatively, and preferably, the water is demineralised.

[0034] The composition of the invention comprises an acid of sufficiently high dissociation constant [Ka] in an amount such that pH of the composition is from 1 to 3. It is preferred that the acid is in an amount such that the pH of the composition is 1, 1.5, 2, 2.5 or 3. Alternatively it is preferred that the composition of the invention comprises an acid of sufficiently high dissociation constant [Ka] in an amount such that pH of the composition is from 0 to 3. As per regulations applicable in various countries or regions of the world, the composition of the invention may comprise an acid of sufficiently high dissociation constant [Ka] in an amount such that pH of the composition is from 1 to 3. In accordance with a preferred aspect, the composition of the invention is an aqueous toilet cleaning composition. Preferably the composition comprises 4 to 15 wt% hydrochloric acid which is an acid of sufficiently high dissociation constant [Ka] and the amount is such that, at least in certain embodiments, the pH of the composition is from 0 to 3.

[0035] It is preferred that the composition of the invention comprises an acid of sufficiently high dissociation constant [Ka] in an amount such that pH of the composition is from 1 to 2, more preferably 1 to 1.5.

[0036] Dissociation constant / Acid dissociation constant (also known as acidity constant, or acidionization constant) is a quantitative measure of strength of an acid in solution. Ka is a way to measure the strength of an acid. It is the equilibrium constant calculated for the ionisation of an acid.

[0037] An acid breaks down into hydrogen ion (H+) and the conjugate base of that acid (A-). Strong acids dissociate completely, while weak acids do not. Strong acids have high Ka values and weak acids have lower Ka values. The strength of an acid is also expressed as pKa, which is negative logio of the corresponding Ka value.

[0038] Preferably the acid is selected from hydrochloric acid, lactic acid, sulphamic acid, phosphorous acid, or citric acid. More preferably the acid is hydrochloric acid. The composition comprises an acid of sufficiently high dissociation constant [Ka] in an amount such that pH of the composition is from 1 to 3. For example, on PubChem and other valid sources of information, the reported values of Ka of HC1 is 1.3 X 106, that of lactic acid is 1.38 x 10'4and that of sulphamic acid is 0.101 Where an acid is dibasic or polybasic (such as phosphoric acid), then reference to Ka is to the first dissociation constant.

[0039] The pH is measured at 25 °C using a standard pH meter. For example, and preferably when the acid is hydrochloric acid, the composition comprises 10 to 15 wt% hydrochloric acid on neat basis. Usually, commercial grade HC1 is available as 30% aqueous solution. It is preferred that the acid is hydrochloric acid. In such cases, it is preferred that that the composition of the invention comprises an acid of sufficiently high dissociation constant [Ka] which is hydrochloric acid in an amount such that pH of the composition is from 1 to 2, more preferably 1 to 1.5. Alternatively, it is preferred that that the composition of the invention comprises an acid of sufficiently high dissociation constant [Ka] which is hydrochloric acid in an amount such that pH of the composition is from 0 to 3, more preferably 0.5 to 2.5, furthermore preferably 0.5 to 2.0.

[0040] Likewise, the acid in the composition can be lactic acid, or citric acid in an amount so that pH of the composition is from 1 to 3, preferably 1 to 2, more preferably 1 to 1.5. For example, as reported on PubChem, the pH of a 10 % aqueous solution of lactic acid is 1.75.

[0041] As there is considerable variation in the dissociation constants of the variety of acids that may be used in the composition of the invention, the composition may comprise any effective amount of the acid, to attain the desired pH of the composition. It is preferred that the composition of the invention comprise an acid of sufficiently high dissociation constant [Ka] in an amount such that pH of the composition is from 1 to 3, alternatively from 0 to 3, and the acid is present in an amount from 5 to 30 wt%, preferably 5 to 20 wt%, more preferably 5 to 15 wt% based on the total weight of the composition.

[0042] Further, it is preferred the composition of the invention comprises a single acid of sufficiently high dissociation constant [Ka] in an amount such that pH of the composition is from 1 to 3, alternatively from 0 to 3. In such cases, it is preferred that the acid is hydrochloric acid, sulfamic acid, lactic acid, citric acid or phosphonic acid. Alternatively, it is preferred that the acid is a combination of one or more of hydrochloric acid, sulfamic acid or phosphonic acid, citric acid, formic acid, oxalic acid, or lactic acid. The choice of acids for combination will depend on the compatibility of the acids and this is within the scope of the common general knowledge of persons skilled in the art. All references to wt% of acids in the compositions is to the percentage by weight of the concerned acid, such as hydrochloric acid.

[0043] The particulate pH-responsive encapsulates

[0044] The composition of the invention comprises particulate pH-responsive encapsulates comprising perfume encapsulated in an encapsulating material which is acid-stable upto pH 3 and is capable of disintegrating to release said perfume at pH beyond 3, where said encapsulates are present in an amount such that said composition comprises 0.1 to 5 wt% of said perfume. Preferably the encapsulates are present in an amount such that said composition comprises 0.2 to 3 wt% of the perfume, more preferably 0.3 to 3 wt% of the perfume. In some embodiments, the perfume is present in an amount 0. 1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.% and so on and so forth up until 5 wt.% and including subranges between 0.1 to 5 wt.%.

[0045] The amount of perfume encapsulated in the encapsulates could vary, depending on the way the encapsulates are made and depending on the nature of the perfume and the encapsulating material. Preferably the particulate pH responsive encapsulates comprise 10 to 80 wt% perfume, more preferably 30 to 60 wt% perfume based on the mass of the particulate encapsulates. The particulate encapsulates comprises perfume as the payload. Depending on the amount of perfume to be included in the aqueous composition of the invention and depending also on the amount of perfume (as payload) encapsulated in the encapsulates, the dosing of encapsulates could vary. In addition, the encapsulates may be in solid or powder form or may be manifested in aqueous form, and in such aqueous form, the actual content of encapsulates in the aqueous medium needs to be factored to be able to ultimately arrive at an aqueous composition of the invention comprising a definite wt% amount of perfume in it, depending on solids content of the aqueous encapsulate medium.

[0046] For example, to be able to formulate an aqueous composition of the invention using encapsulates which are in aqueous format, it could be necessary to add 10 to 20wt% of the aqueous medium containing the encapsulates which in turn would include the encapsulates in an amount such that the composition, i.e. the composition of the invention, comprises 0. 1 to 5 wt% of the perfume.

[0047] The encapsulating material is acid-stable up to pH 3 and is capable of disintegrating at pH beyond 3 to release the perfume. Preferably the encapsulating material is acid-stable in the range of pH 1 to 2, more preferably in the range of 1 to 1.5, and is capable of disintegrating at pH beyond the upper range to release the perfume. In use, when the composition is applied to an acid-resistant hard surface and after allowing for contact time of about 20 to 30 minutes, the surface is washed and rinsed with copious amount of water to ensure spotless cleaning. At this stage the encapsulating material disintegrates because the pH ofthe medium increases beyond 3, usually becomes 5 to 6.5, to thereby release the perfume. The particulate pH-responsive encapsulates respond to change in the pH of the surrounding medium by varying their dimensions. The encapsulating material may swell, collapse, or change depending on the pH of their environment. Usually, such materials contain certain functional groups which may be acidic or basic, responding to either basic or acidic pH values. Such materials are used in controlled drug delivery and surface functionalization.

[0048] The encapsulating material is capable of disintegrating when the composition is diluted with water. Upon dilution with water, the pH of the composition applied to the acid-resistant surface increases progressively until it approaches close to neutral pH. It is believed that when the pH of the composition, i.e. the surrounding medium, increases beyond pH 3 the encapsulating material starts disintegrating and as the pH keeps increasing further the disintegration continues. As the coating disintegrates the encapsulated perfume is released gradually.

[0049] It is preferred that the encapsulating material is calcium shellac, alginate, xanthan gum, polyglutamic acid or a poly carboxylate. Preferably the encapsulating material is calcium shellac. It is preferred that the calcium shellac is prepared by extrusion technique based on mixing aqueous ammonium or sodium shellac solution with calcium chloride solution. Any other suitable method may be used instead.

[0050] As per Yuan etc al., in Volume 109, March 2021, Pages 139-153, in Trends in Food Science & Technology, shellac is an amphiphilic biomacromolecule with a distinctive molecular structure consisting of aleuritic acid and cyclic terpene acids, as mentioned earlier. Depending on the differences between the R and R’ groups, the cyclic terpene acid moiety in shellac can be aleuritic acid, shellolic acid, jalaric acid, laccijalaric acid, laksholic acid, laccishellolic acid, or laccilaksholic acid. The aleuritic acid and cyclic terpene acids are linked by ester bonds and act as the hydrophobic and hydrophilic components ofthe shellac, respectively. Due to carboxyl groups, shellac exhibits the attributes of a weak acid with a pKa of about 6, being dissolvable in water with a pH greater than 7. Under acidic conditions (pH < 7), the protonation of shellac hinders its dissolution. Shellac is insoluble in water, glycerin, hydrocarbon solvents, and esters but soluble in alcohol and organic acids. Shellac is insoluble in weak H-bonded solvents but soluble in moderate to strong H-bonded solvents.

[0051] The particulate pH-responsive encapsulates comprise perfume encapsulated in an encapsulating material. The encapsulating material encapsulates the perfume. The term "perfume" is used in this specification to mean any odoriferous material generally (but not necessarily) having an odour that is considered pleasant or attractive, or any material which acts as a malodour counteractant. The perfumes used in the present invention can be mixtures of conventional perfumery materials. Such materials are, for example, resinoids, resins, and synthetic materials such as hydrocarbons, alcohols, aldehydes, ketones, ethers, acids, esters, acetals, ketals, and nitriles, including saturated and unsaturated compounds, aliphatic, carbocyclic, and heterocyclic compounds.

[0052] The perfume may be synthetic. Any suitable perfume may be used in the composition of the invention. In one aspect of the invention the perfume is acidic in nature. Alternatively, and more preferably the perfume is alkaline. Purpose of the perfume is to provide a perfume boost and pleasant olfactory experience to a consumer at the time of use of the composition of the invention and for a significant amount of time thereafter. The problem with prior art perfumed compositions is that the post-use consumer experience, especially the olfactory experience is not as good. That happens at least to some extent because the fragrance or perfume ingredients are unstable in the acidic medium therefore, neither the composition retains the perfumed nature nor does a user or consumer get a pleasant olfactory experience at the point of use and for an appreciable amount of time immediately thereafter.

[0053] According to a general method of use, the composition of the invention and similar compositions of prior art are first applied to the concerned acid-resistant hard surface, for example, to the rim and bowl and other parts of a WC. Usually, the composition once applied may be spread or evenly applied with a suitably designed brush. The brush also scrubs the surface, and the abrasion improves contact of the composition with the stains or scum on the surfaces. The composition is usually left thereon for about 15 to 20 minutes. Thereafter the composition is washed with copious amounts of water and in the case of WC the commode is flushed clean. At this stage, any impact of the perfume present in the compositions of prior art may be felt for a brief period because major proportion of the perfume is destabilised by the strong acid and any remaining perfume provides a momentary olfactory experience to the consumer. However, in the composition of the invention, it is believed that the polymer, especially the zeta potential property of the polymer stabilises the perfume for longer duration not just in packaged condition but also ensures prolonged and sustained release of the perfume when the composition is used on an acid-stable surface.

[0054] The polymer

[0055] The encapsulating material comprises a polymer having zeta potential of -30 mV to -80 mV. Without wishing to be bound by theory it is believed that due to the polymer, the perfume is released for a prolonged period in a gradual manner. The consumer gets better olfactory experience due to the aforesaid phenomenon. Zeta potential can be defined as electric potential in the interfacial double layer, which is between the stationary layer of fluid attached to the dispersed particles and the dispersion medium.

[0056] Preferably the pH responsive coating comprises a polymer having zeta potential of -30 mV to -80 mV, where the zeta potential is determined at pH 1 to 3. Zeta potential of the polymer may be determined by any means and method known in the art.

[0057] It is particularly preferred that the polymer having zeta potential of -30 mV to -80 mV is xanthan gum. It is preferred that the encapsulating material and the polymer having zeta potential of -30 mV to -80 mV are not identical. Preferably the pH-responsive perfume encapsulates comprise 0.5 to 5 wt% of the polymer having zeta potential in the range of -30 mV to -80 mV. In some embodiments, the polymer is present in an amount of 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.% and so on and so forth, up until 5 wt.% and including subranges of the range 0.5 to 5 wt.%.

[0058] It is observed that the aqueous composition of the invention is translucent, presumably due to presence of the particulate pH-responsive perfume encapsulates. It is preferred that the particle size of the particulate pH-responsive perfume encapsulates is 10 to 200 pm, as measured by Malvern Mastersizer® based on laser diffraction method with laser obscuration of 3.59 %. It is preferred that the composition is turbid. Turbidity of the composition is from 200 to 700 NTU. The particulates scatter incident light thereby giving the translucent effect. The translucent nature is visible even when the composition comprises a water-soluble dye. Preferably the dye is blue in colour, such that the composition has a blue appearance. Alternatively, the composition of the invention is dye -free.

[0059] Other preferred ingredients

[0060] It is preferred that the aqueous composition of the invention comprises a thickener. In such cases the viscosity of said composition is preferably from 100 to 2000 cP. A viscous composition has beter flow properties and can retain longer on the typical contoured or inclined hard surfaces. If no thickener is used the composition may run down the side of the toilet bowl too quickly without effectively cleaning the surface. However, if the composition becomes too viscous the product may lose cleaning performance, and the aesthetic appeal of the composition may be affected. The aqueous composition can be desirably provided as a ready to use product in a pourable or manually squeezable botle (deformable botle) with appropriately designed angular neck and dispensing orifice. It is preferred that the thickener is selected from the group consisting of quaternary ammonium halides, tertiary amine ethoxylates, acrylic copolymer, xanthan gum, substituted cellulose and polysaccharide. Preferably the composition comprises 0.25 to 1.25 wt%, more preferably 0.75 to 1.25 wt% thickener, which preferably is an acrylic copolymer.

[0061] Other ingredients such as pH adjusters, stabilizing agents, preservatives, free fragrances and dyes may be included in the liquid cleaning composition of the present invention. Stabilizing agents may be included to achieve phase stability, pH balance and other desired characteristics. The pH of the composition of the invention is from 1 to 3. Alternatively, the pH of the composition of the invention is from 0 to 3.

[0062] Water

[0063] The composition of the invention is preferably an aqueous composition. Preferably the composition comprises 40 to 80 wt% water. Some amount of the water contained in the composition maybe atributable to certain ingredients, for example, hydrochloric acid which is commercially available as a 30% aqueous format.

[0064] Nonionic surfactant

[0065] The aqueous composition of the invention preferably comprises 1 to 10 wt% nonionic surfactant. More preferably the composition comprises 1 to 5 wt% nonionic surfactant and still more preferably 2 to 3 wt% nonionic surfactant.

[0066] It is preferred that the nonionic surfactant is C8 to C16 alkyl polyglucoside or a C8 to Cl 8 faty alcohol ethoxylate. Further preferably HLB value of the C8 to C 18 faty alcohol ethoxylate is from 11 to 20. Nonionic surfactants consist of a hydrophobic moiety, such as a C8-C20 faty acid amide and a hydrophilic moiety. These nonionic surfactants are, for instance, alkoxylation products of the above hydrophobic moieties containing from 2 to 30 moles of alkylene oxide. In one aspect it is preferred that the nonionic surfactant is a fatty alcohol ethoxylate. In such cases it is preferred that the nonionic surfactant is a Cs-Cn primary alcohol containing 4 to 9 moles of ethylene oxide, preferably a primary alcohol containing 6 to 12 moles of ethylene oxide. Preferably the non-ionic surfactant is selected from the Brij® 35 or Brij® 97 which are branded surfactants. When the nonionic surfactant is a fatty acid ethoxylate it is preferred that the surfactant is Myq® S20 or Myq® S40, or PEG- 100 stearate.

[0067] Alternatively, the non-ionic surfactant is alkyl polyglucoside. The alkyl radical is generally referred a range of carbon atoms (e.g., C8 / 10) and the degree of polymerization is generally the average degree of polymerization of the mixture. An example of suitable alkyl polyglucoside is Glucopon® ex. BASF.

[0068] When the nonionic surfactant is a polyoxyethylene sorbitan alkyl ester, it is preferred that the surfactant is Tween® 21 or Tween® 20 which are branded products.

[0069] Amphoteric surfactant

[0070] The composition of the invention preferably comprises an amphoteric surfactant. When present, the composition comprises 0.1 to 5 wt% amphoteric surfactant, more preferably 0.5 to 4 wt%. It is preferred that the amphoteric surfactant is an amine oxide, alkyl betaine, alkyl amido propyl betaine, alkyl sulphobetaine or a combination thereof. It is preferred that the amine oxide is selected from alkyl dimethyl amine oxide, alkyl amido propyl dimethyl amine oxide and combinations thereof. Examples includes lauryl dimethylamine oxide, coco dimethyl amine oxide and coco amido propyl dimethyl amine oxide.

[0071] When the amphoteric surfactant is a betaine it is preferred that the betaine is alkyl betaine, alkyl amido betaine, alkyl amidopropyl betaine, alkyl sulphobetaine and alkyl phosphobetaine, wherein the alkyl group may have carbon chain length of C8 to C20. It is preferred that the betaine is cocodimethyl sulphopropyl betaine, cetyl betaine, laurylamidopropyl betaine, caprylate / caprate betaine, capryl / capramidopropyl betaine, cocamidopropyl hydroxysultaine, cocobutyramido hydroxysultaine, and preferably lauryl betaine, cocamidopropyl betaine and sodium cocamphopropionate. Most preferably the betaine is cocamidopropyl betaine (CAPB).

[0072] Antimicrobial agent

[0073] It is preferred that the composition of the invention comprises an antimicrobial agent. Preferably the composition comprises from 0.01 to 2.0 wt% antibacterial agent. It is preferred that the antimicrobial agent is a quaternary ammonium halide, more preferably it is an alkyl ammonium halide such as cetyl trimethyl ammonium bromide, alkyl aryl ammonium halides such as octadecyl dimethyl benzyl ammonium bromide, N-alkyl pyridinium halides for example N- cetyl pyridinium bromide, dodecylbenzyltrimethyl ammonium chloride, cetrimonium chloride, or benzalkonium chloride. A variety of such quaternary compounds are available under the trademarks EMPIGEN, BARDAC, BARQUAT, HY AMINE, LONZABAC, and ONYXIDE.

[0074] Composition of the invention preferably comprises a dye, more preferably acid blue or red dye, such as Acid blue 80 CI 61585 and Acid Red 52 CI 45100, CI Direct dyes as well as other colorants permitted by regulation.

[0075] Method

[0076] In accordance with a second aspect disclosed is a method of cleaning acid-resistant hard surfaces comprising the steps of: i) applying thereto an aqueous composition for cleaning acid-resistant hard surfaces of the first aspect; ii) allowing for a contact time of 5 to 30 minutes; and iii) rinsing said surface with water, wherein said method provides at least 99% or 2-log germ kill of microbes present on said hard surface.

[0077] Preferably the contact time is 10 to 20 minutes. Preferably the acid-resistant hard surface is a of kitchen worktop, kitchen floor, sink, kitchen counter-top, floor, bathroom tile, toilet bowl or a commode.

[0078] Preferably the composition of the present invention provides at least 2-log germ kill against one or more of Enterococcus hirae, Escherichia Coli, Staphylococcus aureus or Pseudomonas aeruginosa.

[0079] The composition of the invention may comprise preservatives in minor amounts. It is preferred that the preservative includes those available under the trademarks Kathon® or Suttocide® in amounts of 0.01 to 1 wt% of the composition.

[0080] The composition of the invention is preferably provided as a ready to use product in a manually operated spray-dispensing container or in a deformable squeeze-bottle type dispenser. Such bottles and packs are generally made of synthetic polymers such a polyolefin (e.g., polyethylene, polypropylene) or PET, from which the liquid composition is expelled, typically via a nozzle, by a user compressing part of the deformable bottle.

[0081] Examples

[0082] The invention will now be explained in detail with reference to the following non-limiting exemplary embodiments. All chemicals are from synthetic origin procured from commercial sources. The invention is not based on any bioresource obtained from India. No bioresource obtained from India was used in any of the examples disclosed herein.

[0083] Example 1:

[0084] An aqueous composition for cleaning acid-stable hard surfaces as per the invention was prepared. Details are shown in Table 1.

[0085] Table 1

[0086] Oleylamine Ethoxylate is a thickener surfactant; Cetrimonium chloride is a quaternary ammonium chloride.

[0087] Note:

[0088] The particulate pH-responsive encapsulates are present in an amount such that the composition comprises 0. 1 to 5 wt% of the perfume. See Table 2b for the formulation of the encapsulates.

[0089] The formulation of the pH-responsive encapsulates is shown in Table 2a. An alternative formulation is shown in Table 2b. Table 2a

[0090] Table 2b **In the case of formulation of Table 1, the corresponding amount of encapsulates turns out to be about 16 wt% considering the solids content and perfume content of formulation 2b. The composition of Table 1 contained 16 wt% of the composition of Table 2a / 2b, thereby composition of Table 1 effectively contained 0.32 wt% perfume in encapsulated form. Therefore, in the composition of Table 1 (aqueous composition for cleaning acid-stable hard surfaces of the invention), an appropriate amount of encapsulate (16 %) was added which in turn contained the indicated amount of perfume.

[0091] Example 2 (comparative): Two compositions outside the invention were prepared for comparative evaluation. Details and important properties are shown in Table 3.

[0092] Table 3

[0093] Example 2

[0094] In this experiment the composition of Table 1 was tested against comparative compositions A and comparative composition B of Table 3. Samples of all 3 compositions were stored at 40 °C for three weeks after preparing in the lab.

[0095] Agilent GC coupled with MS was used for the analysis. The mixture was separated on a fused silica capillary column (HP-5MS) (5% phenyl methyl siloxane), in a temperature program upto 50°C and the flow rate of helium as carrier gas was 1 ml / minute. The Hewlett Packard quadrupolar mass spectrometer model 5989B had an electron energy of 70 eV. One m of encapsulated fragrance solution (shellac based encapsulates) was diluted with 9 m of water. It was expected that upon dilution with water the pH of the medium would increase beyond 3 thereby causing disintegration of the encapsulating material to further cause release of the encapsulated perfume. The extent of release of the perfume was determined by conducting GC analysis of an aliquot of the diluted composition at time=I5 minutes (after dilution). One mb of sample was injected into a GC vial which was sealed by crimping for head-space analysis of the volatile fragrance molecule . The primary peak observed in the GC-MS graph corresponds to diphenyl ether (a component of the fragrance) at an elution time of 16.3 minutes. The data was captured in terms of area under the respective peaks, greater area meant more stable perfume.

[0096] The data as observed in a GC-MS headspace experiment is shown in Table 4.

[0097] Table 4

[0098] The data for Comparative-B indicates that particulate pH-non-responsive encapsulates (melamineformaldehyde) are not as stable compared to the composition of Table 1, which is evident from lesser area under the peak.

[0099] Example 3

[0100] In the experiment a composition as per Table 1 was used after it had been stored at 40 °C for three weeks. A 5 ml sample of the composition was added to 100 ml water to simulate a real-life in-use situation. It was expected that upon dilution with water, the pH of the medium would increase beyond 3 thereby causing disintegration of the encapsulating material thereby causing release of the perfume encapsulated therein. The extent of release of the perfume was determined by gas chromatographic analysis of an aliquot of the diluted composition at time=zero (immediately after dilution) and thereafter after 5 minutes and 15 minutes post-dilution. The data is shown in Table 5. The data was captured in terms of area under the respective peaks, greater area meant more stable perfume.

[0101] Table 5

[0102] Note:

[0103] All compositions of Table 1 tested about were made with perfume encapsulate formulation 2b.

[0104] This data shows sustained and steady release of perfume up to 15 minutes after dilution which simulates a real-life in-use situation when such compositions are washed off from the acid- resistant surfaces using copious amount of water, despite being stored at 40°C for 3 weeks.

[0105] Example 4

[0106] In the experiment a composition as per the invention and as per Table 1 was prepared. An alternative composition according to the invention but without the blue dye was also prepared. Turbidity of the compositions was determined. The data is shown in Table 6.

[0107] Table 6

[0108] The data indicates that Comparative composition-A was much less turbid. The illustrated examples indicate that in the field of perfumed aqueous acidic cleaning compositions, the present invention addresses the need of stabilising standard perfume or fragrance ingredients for longer duration in highly acidic medium and which can be released upon dilution with water without necessarily needing any shear force.

Claims

CLAIMS1) An aqueous composition for cleaning acid-resistant hard surfaces, said composition comprising: a) an acid of sufficiently high dissociation constant [Ka] in an amount such that pH of said composition is from 1 to 3; and b) particulate pH-responsive encapsulates comprising perfume encapsulated in an encapsulating material which is acid-stable upto pH 3 and is capable of disintegrating to release said perfume at pH beyond 3, where said encapsulates are present in an amount such that said composition comprises 0. 1 to 5 wt% of said perfume, wherein, said encapsulating material comprises a polymer having zeta potential of -30 mV to -80 mV.2) The aqueous composition as claimed in claim 1, wherein said acid is selected from hydrochloric acid, lactic acid, or citric acid.3) The aqueous composition as claimed in claim 2, wherein said acid is hydrochloric acid.4) The aqueous composition as claimed in any of claims 1 to 3, wherein said encapsulating material and the polymer having zeta potential of -30 mV to -80 mV are not identical.5) The aqueous composition as claimed in any of claims 1 to 4, wherein said encapsulating material is calcium shellac, alginate, xanthan gum, polyglutamic acid or a poly carboxylate.6) The aqueous composition as claimed in claim 5, wherein said encapsulating material is calcium shellac.7) The aqueous composition as claimed in claim 5 or 6 wherein said polymer having zeta potential of -30 mV to -80 mV is xanthan gum.8) The aqueous composition as claimed in any of claims 1 to 7, wherein said particulate pH- responsive encapsulates comprise 10 to 80 wt% perfume.9) The aqueous composition as claimed in any of claims 1 to 8, wherein said perfume is alkaline.10) The aqueous composition as claimed in any of claims 1 to 9, wherein said pH-responsive perfume encapsulates comprise 0.5 to 5 wt% of said polymer having zeta potential -30mV to -80 mV.11) The aqueous composition as claimed in any of claims 1 to 10, wherein particle size of said particulate pH-responsive perfume encapsulates is 10 to 200 pm, as measured by Malvern Mastersizer® based on laser diffraction method with laser obscuration of 3.59 %.12) The aqueous composition as claimed in claim 11, wherein said composition is turbid and turbidity of said composition is from 200 to 700 NTU.13) The aqueous composition as claimed in any of claims 1 to 12, wherein said composition comprises a thickener.14) The aqueous composition as claimed in claim 13, wherein said thickener is selected from the group consisting of quaternary ammonium halides, tertiary amine ethoxylates, acrylic copolymers, xanthan gum, substituted cellulose and polysaccharide.15) The aqueous composition as claimed in claim 13 or 14, wherein viscosity of said composition is 100 to 2000 cP.16) A method of cleaning acid-resistant hard surfaces comprising the steps of: i) applying thereto the aqueous composition for cleaning acid-resistant hard surfaces as claimed in claim 1 ; ii) allowing for a contact time of 5 to 30 minutes; and iii) rinsing said surface with water, wherein said method provides at least 99% or 2-log germ kill of microbes present on said hard surface.17) An aqueous composition for cleaning acid-resistant hard surfaces for use to provide at least 99% or 2-log germ kill of microbes present on said hard surface, where said composition comprises:a) an acid of sufficiently high dissociation constant [Ka] in an amount such that pH of said composition is from 1 to 3; and, b) particulate pH-responsive encapsulates comprising perfume encapsulated in an encapsulating material which is acid-stable upto pH 3 and is capable of disintegrating to release said perfume at pH beyond 3, where said encapsulates are present in an amount such that said composition comprises 0. 1 to 5 wt% of said perfume, wherein, said encapsulating material comprises a polymer having zeta potential of -30 mV to -80 mV.18) Use of the composition as claimed in claim 1 to provide at least 99% or 2-log germ kill of microbes present on hard surface.

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