Field of the Invention

The invention relates to a solid concentrated surface cleaning and disinfection composition. The invention more particularly relates to a disinfection composition in the powder or tablet form that is diluted with water before being used for disinfecting any surface whether it be an animate or an inanimate surface. The composition has been tailored to generate quick dissolution in water upon such dilution and this composition also surprisingly provided enhanced antimicrobial efficacy especially against gram negative bacteria.

Background of the Invention

Compositions for disinfecting and cleaning inanimate hard surfaces like floors, walls, windows, doors, furniture, and table tops in various indoor and outdoor locations are known. Toilets and bathrooms are other places where germs proliferate and disinfection and cleaning compositions are widely used. Other types of hard surfaces that are cleaned by such compositions include articles found in households, offices and other public places. They may also be used for disinfecting soft inanimate surfaces like clothes, bedsheets, pillow covers and upholstery like curtains. Such compositions are often sold in liquid form, usually as a concentrate in a bottle or as a solid e.g in powder or tablet form. The consumer then dilutes the composition with large quantities of water before using the product on the desired surface.

These products may also be used for sanitizing topical surfaces of the human or animal body. They may be used as bath water, as water used for shaving, cleaning babies between diaper changes, for disinfecting pets and for sanitizing hands at homes, hospitals and in medical clinics; among a host of other personal sanitizing applications.

Popular classes of disinfecting I sanitizing actives include bleaches, phenolics and quaternary ammonium surfactants. Of these, quaternary ammonium surfactants are considered to be safe and compatible for use both on inanimate as well as on animate surfaces like skin of animals and humans. However, quaternary ammonium compounds are highly hygroscopic materials, and are therefore obtained as sticky or pasty semi-solid masses, which are difficult to handle and process.

Cleaning and disinfecting compositions are sold in various forms like liquids, bars, tablets, and powders. While liquid compositions have high quantity of water, solid forms contain a large percentage of structuring ingredients that gives it the desired shape and form. The inclusion of water and inert structuring ingredients adds to the weight and volume of the products that not only makes for more expensive packaging cost but also to the cost of transporting such products from the manufacturing site to the homes of the consumers. Many products have been formulated and sold in the concentrated form to solve the above problem. Such concentrated products have minimal amount of inert material used for structuring the solid product and minimal amount of water in liquid products. Such products in the concentrated form, whether in the solid or liquid form is diluted by the consumer before use.

The present inventors were working on providing such kind of concentrated products for cleaning and disinfection using quaternary ammonium surfactants but found that it was difficult to ensure quick dissolution of the concentrate in water especially when the product was in solid form. The inventors believe, without wishing to be bound by theory, that this happens because when the solid surfactant first comes in contact with water, the outer surface of the surfactant particle/ granule forms a gel phase which impedes further dissolution of the surfactant. One of the popular ways of solving this problem is by providing an effervescent product by including an acid and an alkali therein which when added to water during the dilution by the consumer, react to cause the formation of inert gases e.g. carbondioxide formed by reaction of sodium carbonate and citric acid. The present inventors found that such a solution to the dissolution problem was not very efficient when the disinfectant was a quaternary ammonium surfactant although they tried all sorts of optimizations like varying the type and amounts of acid and alkalis, and their relative ratios, inclusion of disintegrating agents and/or tableting excipients, and use of bilayer tablets. They found that the above approaches could not solve the problem to the desired degree. The problem was further compounded when the composition required the inclusion of yet another cleaning agent like a non-ionic surfactant.

The present inventors with their extensive experience in the area of phase behaviour of multicomponent liquids and by carrying out a large number of experiments, have come up with a solution to the above problem. It involves delivering the surfactant actives through an adduct with urea. US2676955 discloses urea adducts of quaternary compounds.

It was surprisingly found that not only can the disinfecting active like a quaternary ammonium surfactant be delivered through this route but a cleaning agent like a non-ionic surfactant can also be included while ensuring the fast dissolution kinetics. Further, the present inventors also surprisingly found enhanced antimicrobial efficacy of the composition of the invention as compared to one having the quaternary ammonium surfactant alone, especially against gram negative bacteria.

An additional benefit of delivering the solid concentrated cleaning composition is that due to minimal or no water in the composition, a preservative needs to be included only in minimal quantity or need not be used at all.

It is thus an object of the present invention to provide for a solid concentrated cleaning composition which when diluted in water dissolves very quickly in the order of seconds.

It is another object of the present invention to provide for a solid concentrated cleaning composition that is not hygroscopic and therefore stable on storage.

It is another object of the present invention to provide for enhanced antimicrobial efficacy especially against gram negative bacteria.

Summary of the Invention

According to the first aspect of the invention there is provided a solid concentrated cleaning composition comprising an adduct of urea with a mixture of quaternary ammonium surfactant and a non-ionic surfactant.

Another aspect of the present invention relates to a method of ensuring fast dissolution of a composition comprising a surfactant mixture of a quaternary ammonium surfactant and a nonionic surfactant comprising the step of including an adduct of the surfactant with urea in the composition

Yet another aspect of the present invention relates to a process for preparing a solid concentrated cleaning composition of the first aspect comprising the steps of:

(i) dissolving the urea and the surfactant in desired quantities in a solvent preferably water;

(ii) heating the solution to about 40 to 70 °C until a clear solution is obtained; followed by

(iii) drying the solution to a powder.

A further aspect of the present invention relates to a method of cleaning and disinfecting a surface comprising the steps of dissolving the composition of the first aspect in water at a desired dilution ratio and applying the composition to the desired surface, followed optionally with a step of rinsing or wiping the surface to be substantially free of said composition.

Detailed Description of the Invention

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 utilised 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 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”. Unless specified otherwise, 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.

The first aspect of the invention provides for a solid concentrated cleaning and disinfecting composition comprising an adduct of a surfactant mixture of a quaternary ammonium surfactant and a non-ionic surfactant, with urea. The composition of the invention is a solid concentrate for use in disinfection of desired surfaces. The composition is considered as a concentrate since it is usually to be used after diluting with water in which the solid dissolves after which it is applied on the desired surface for disinfection. It is envisaged that the composition may be dissolved in water in a weight ratio which is preferably in the range of 1 :100 to 1 :1000.

In personal care applications it may be used as an antiseptic liquid for disinfection of hands and other bodily surfaces which are generally considered the nodal points for spreading diseases. In such cases the solid composition of the invention may preferably be dissolved in water in a weight ratio in the range of 1 :100 to 1 :300. The product is especially preferred for use with such large dilutions in various other applications meant for disinfection of inanimate surfaces. Such surfaces include disinfection of floors, kitchen tops, bathrooms in homes, and public places like offices, hotels, and restaurants. They may also be used to disinfect places which are known to have a high density of sick people like in hospitals, clinics and other healthcare facilities.

Other inanimate surfaces include soft surfaces like clothes and upholstery. The compositions dissolved in water may be used for disinfecting clothes that are considered dirtier like underwear or clothes used for sports or for use in the gyms. These clothes are soaked in such disinfectant solutions before putting them in a washing machine for regular washing and cleaning. Alternately the clothes already handwashed or machine washed may be soaked and rinsed in the composition of the invention which is diluted in water, before they are dried to ensure that any residual germs are killed before the next use by the consumer. In all of the above high dilution cases, the composition of the invention may be diluted in water in a weight ratio in the range of 1 :40 to 1 :300, preferably 1 : 100 to 1 : 300.

The composition of the invention comprises a disinfecting active which is cationic in nature viz. a quaternary ammonium surfactant. The quaternary ammonium surfactant is preferably chosen from one or more of alkyl dimethyl benzylammonium chloride (ADBAC), alkyl dimethyl ethylbenzyl ammonium chloride(DEBAC), didecyl dimethyl ammonium chloride (DDAC), cetyl trimethyl ammonium chloride (CTAC), and cetyl pyridinium chloride (CPC). More preferred quaternary ammonium surfactant is chosen from one or more of ADBAC and DDC, most preferably it is ADBAC. ADBAC is also known as benzalkonium chloride (BKC).

The composition comprises 10 to 35%, preferably 20 to 25% quaternary ammonium surfactant, included as part of the adduct. The percentage is by total weight of the composition.

The benefit of the invention of ensuring quick dissolution of the surfactants. This could be achieved in one of two ways. In the first way one could prepare an adduct of the quaternary ammonium surfactant with urea. Subsequently an adduct of a non-ionic surfactant with urea could be prepared. The two adducts could then be mixed. A second and a more preferred way is to prepare an adduct of urea with a mixture of the quaternary ammonium surfactant and the non-ionic surfactant, for inclusion in the composition of the invention.

The composition comprises 20 to 70%, preferably 40 to 50% urea, included as part of the adduct. The percentage is by total weight of the composition. Preferred non-ionic surfactants with which an adduct with urea may be prepared as per the present invention are alkyl (C8-C15) poly glucoside and fatty (C9 to C18) alcohol ethoxylate (EO3 - EO23). Preferred of these two is alkyl (C8-C15) poly glucoside (APG). Suitable non-ionic surfactants which may be included in the composition of the invention are commerically available as Glucopon 425 N/HH, Glucopon 215 UP, Glucopon 420 UP

The composition comprises 3.0%, to 9.0%, to preferably 5.0 to 7.0% non-ionic surfactant, included as part of the adduct. The percentage is by total weight of the composition.

The weight ratio of the quaternary ammonium surfactant to urea in preparing the adduct is preferably in the range of 1 :1 to 1 : 7. The weight ratio of the non-ionic surfactant to urea in preparing the adduct is preferably in the range of 1 :2 to 1 :25.

The most preferred aspect of the invention relates to providing an adduct of urea with a mixture of the quaternary ammonium surfactant with the non-ionic surfactant. Thus the adduct is prepared in a single pot where all the three ingredients are included to form a single adduct.

The composition of the invention may optionally include a processing aid selected from one or more of mannitol, cellulose, starch and sorbitol. Of these, mannitol is most preferred. The processing aid when included, is preferably present in 10 to 35%, preferably 20 to 25% by weight of the composition.

The composition may further comprise various additional ingredients known to a person skilled in the art. Such additional ingredients include but are not limited to: perfumes, pigments, preservatives, emollients, emulsifiers, gelling agents, or thickening agents.

The antimicrobial composition is in the solid form preferably as a powder or as a tablet. The tablet may be prepared by taking the powder prepared as per the process of preparation of the invention and tableting it. Powder forms of the product are most preferred.

The powder form of the product may be sold as a unit dose by packing desired amount of the product in a sachet. The consumer has to cut the sachet and add the unit dose contents of the sachet into desired amount of water and stir for a short period of time say 10 seconds to a minute and the powder fully dissolves. For hard surface and laundry disinfection and cleaning, the contents of the sachet may be added to a bucket of water and stirred to prepare the disinfecting solution to wipe floors or other hard surfaces or to soak their clothes in for the desired benefit.

For personal care applications like disinfection of hands, the sachet may be added to a bottle of water and shaken to let the ingredients dissolve. The concentrated liquid in the bottle may then be used as and when required for hand washing.

Such a sachet may generally contain 3 to 6 g of powder as a unit dose. Alternately a tablet in similar weight range may be packed in such a sachet as a unit dose.

The present invention also relates to a process for preparing the solid concentrated cleaning composition of the invention comprising the steps of:

(i) dissolving the urea and the surfactant in the desired quantities in a solvent preferably water;

(ii) heating the solution to about 40 to 70 °C until a clear solution is obtained; followed by

(iii) drying the solution to a powder.

The solvents which may be used are ethanol, propyl alcohol, isopropyl alcohol, butyl alcohol or water. The most preferred solvent is water. Further details on the various conditions under which the process may be carried out are given below.

To make about 1 kg of the composition, the following process may be used. About 200 to 250 g of urea and BKC solution (50%) in the range of 400 to 500 g along with mannitol in the range of 200 to 250 g and APG in the range of 100 to 125 g are taken in a glass beaker. About 400 to 500 g of water is added to the same glass beaker. The mixture is heated to a temperature between 40 and 70 °C till the solution become clear. This clear solution is then transferred to a tray with large surface area. This tray is heated overnight in an oven at temperature in the range of 60 to 70 °C to prepare a dry powder. This dry powder is then milled and sieved through a 40 mesh sieve to get uniform particles of the adduct.

The invention also relates to a method of cleaning and disinfecting a surface comprising the steps of dissolving the composition of the invention in water at a desired dilution ratio and applying the composition to the desired surface, followed optionally with a step of rinsing or wiping the surface to be substantially free of the composition. The pH of the diluted composition is preferably in the range of 6 to 8. The invention also relates to a method of providing enhanced antimicrobial efficacy especially against gram negative bacteria which method comprises the step of dissolving the composition of the invention in water at a desired dilution ratio and applying the composition to the desired surface, followed optionally with a step of rinsing or wiping the surface to be substantially free of the composition. It is observed that enhanced antibacterial efficacy of the composition of the invention is obtained as compared to one having quaternary ammonium surfactant alone (without adduct formation with urea) against gram negative bacteria like E. Coli while the efficacy was about the same against gram positive bacteria like S. aureus, E. hirae and P. aeruginosa.

The invention will now be illustrated with the help of the following non-limiting examples.

Examples

Examples A-D: The following tablet compositions of 5 gm each with a diameter of 25 mm was prepared using a tableting pressure of 10 kgf, as shown in Table - 1 below.

The dissolution time of these tablets were measured using the procedure given below:

To find the dissolution time, each tablet was separately dropped in one litres of water. Dissolution time is the time taken to get a no residual water and it was measured using a stopwatch.

Table -1

The data in the table above indicates that an effervescent tablet which includes BKC, APG or a mixture of BKC and APG takes a long time to dissolve.

Example - 1

An adduct of BKC and APG with urea was prepared as follows. Required quantity of urea, BKC and Glucopon 425N/HH was mixed in 47 g water. The mixture was heated to 60°C to form a clear solution. The solution was poured on to a petridish and allowed to dry to a cake in an oven at 70 °C. The cake was powdered to a uniform size to pass 40 mesh screen to prepare the desired adduct. A hygiene composition using the above adduct with processing aid mannitol as shown in table -2 below was prepared.

Table - 2:

The weight of the ingredients in the above table is given on dry weight basis.

The dissolution kinetics of the above formulation was measured by taking 1 g of the above formulation in 70 ml water in a beaker and stirred by hand with a glass rod. The powder was seen to dissolve in about 13 - 15 seconds.

In contrast, equivalent amount of BKC powder (0.235 g) was taken in 70 ml of water and stirred similarly. The powder did not dissolve completely even after 30 minutes of stirring.

The observation above shows that composition as per the invention (Example -1) provides for vastly superior rate of dissolution as compared to using the individual ingredient (BKC) alone.

Example E, 1 : Antibacterial efficacy of composition of the invention as compared to one outside the invention.

A commercially available liquid floor cleaner composition (Example - E) was taken having the ingredients as shown in table - 3. The antibacterial efficacy of this composition was compared to that of composition as per the invention (Example -1).

Table -3:

The above compositions were tested against bacteria S. aureus, E. Coli, P. aeruginosa and E. hirae using EN1276 under condition of 1 gram/ liter (gpl) with 15 minute contact time of the composition with BSA content of 0.03 wt%. Liquid composition of Example E was diluted by taking 75 ml of the composition in 1 liter of water. 2.5 g of powder composition of Example 1 was dissolved in 1 lit of water. The above dilutions ensured that both compositions were tested using sample containing 0.56 g BKC.

The log kill obtained using the composition on the various bacteria is given in Table - 4 below.

Table- 4:

Example F, G: Admixtures of solid ingredients and its impact on dissolution kinetics

Example F corresponds to an admixture of the ingredients shown in Table -2 where the solid ingredients in powder form were mixed at 25 °C.

Example G was prepared by mixing solid powder ingredients as shown in Table -5 below

Table - 5:

The dissolution kinetics of the above samples was measured by taking 1 g of the above powder compositions in 70 ml water in a beaker and stirred by hand with a glass rod. The powder in Example F took about 5 minutes to dissolve while the one of Example G took about 12 minutes to dissolve. This is in contrast to Example 1 where the product was prepared as an adduct of APG and BKC with urea which took only about 13-15 seconds to dissolve. The data above proves that mere admixtures of the powders deliver poor dissolution kinetics as compared to a composition of the invention.