Field of the Invention

The present invention relates to a liquid dishwash composition. It particularly relates to a liquid composition that not only cleans better but also effectively provides superior disinfection.

Background of the Invention

Disinfecting and cleaning compositions are of great benefit to individuals, since proper use generally may reduce the number of germs and pathogens the individual is exposed to. Such compositions are used for cleaning hard surfaces e.g. those in the kitchen like utensils, stoves and table tops. Disinfecting action can be achieved by including conventional bleaches like hypochlorite in such compositions but many consumers do not like the smell of chlorine that is generated during the use of such compositions. Compositions comprising organic acids which work at low pH (in the range of 3 to 5) have also been used but they do not fully provide the desired cleaning benefit. When such low pH compositions comprising organic acids are adapted to higher pH (of about 9 to 11), the compositions are found to clean better but are found to be wanting in terms of delivering the desired disinfection. The present inventors therefore sought to find a solution to this problem of delivering high pH compositions that not only deliver the high desired disinfection (against both gram positive as well as gram negative bacteria) but achieve this without the use of harsh bleaching agents. They also sought to develop a product using a judicious combination of commonly used ingredients such that the product can be produced at low cost thereby being cost-effective for use by every strata of society. Further, they worked to develop this product to be at low enough a viscosity that it is sprayable from a hand held pump. After extensive experimentation, they arrive at a selective combination of two anionic surfactants, one non-ionic surfactant, a biodegradable chelating agent and solvent each of them combined in a narrow window of concentration to get all of the above desired properties from the composition so developed.

To the knowledge of the present inventors such a combination of actives to achieve the desired product characteristics has not been disclosed or used in the past.

It is thus an object of the present invention to provide for a liquid dishwash composition which provides the desired cleaning as well as disinfecting action at high pH against both gram negative as well as gram positive bacteria. It is another object of the present invention to provide for a liquid dishwash composition which delivers the above disinfecting action through a sprayable composition.

Summary of the Invention

According to the first aspect of the present invention there is provided a liquid dishwash composition comprising

(a) 1 to 7.5 wt% of a primary surfactant selected from alkyl ether sulphate or alkyl benzene sulphonate;

(b) 2 to 4 wt% alkyl polyglucoside surfactant;

(c) 2.5 to 7.5 wt% alkyl sulphate surfactant;

(d) 0.5 to 2 wt% a biodegradable chelating agent;

(e) 0.5 to 1.5 wt% C2 - C3 phenoxy alkanol, preferably phenoxy ethanol.

Another aspect of the present invention provides for a method of disinfecting a surface comprising the steps of applying the composition of the first aspect on to a surface followed optionally by rinsing the surface free of the composition.

Detailed Description of the Invention

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". Thus, the term "comprising" is meant not to be limiting to any subsequently stated elements, but rather to optionally also encompass nonspecified elements of major or minor functional importance. In other words, the listed steps or options need not be exhaustive. Whenever the words "including" or "having" are used, these terms are meant to be equivalent to "comprising" as defined above. 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. Except in the 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 "x to y" are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format "x to y", it is understood that all ranges combining the different endpoints are also contemplated. Unless specified otherwise, amounts as used herein are expressed in percentage by weight based on total weight of the composition and is abbreviated as “wt%”. Throughout this description, the term ‘disinfection’ refers to reduction of the number of viable microorganisms in a given medium or on a given surface. Typically, disinfection involves the destruction or inactivation of the microorganisms. Both animate and inanimate media and surfaces are contemplated, although inanimate surfaces are preferred. It is preferred that the disinfection is to the extent of at least 3 log reduction of viable microorganisms.

The term " antimicrobial " refers to a compound capable of killing, inhibiting the growth of, or controlling the growth of microorganisms at a locus; antimicrobials include bactericides, fungicides and algaecides. The term "microorganism" includes, for example, fungi (such as yeast and mould), bacteria and algae.

The compositions of the present invention are preferred for non-therapeutic use, and more particularly preferred for use in cleaning surfaces, preferably wherein the surface is a hard surface in the kitchen especially utensils and dishes.

The composition comprises of a primary surfactant selected from alkyl ether sulphate or alkyl benzene suphonate. The alkyl ether sulphate surfactant for inclusion in the composition of the invention preferably has 10 to 18 carbon atoms, more preferably C10 to C12 carbon atoms. The alkyl ether sulphate surfactant preferably has one to ten ethylene oxide or propylene oxide units per molecule, preferably one to three ethylene oxide units per molecule. The surfactant has a counterion which is an alkali metal such as sodium or potassium; or an ammoniacal counterion such as monoethanolamine, (MEA) diethanolamine (DEA) or triethanolamine (TEA). Preferably it is sodium or potassium, most preferably it is sodium. The most preferred surfactant of this class for inclusion in the composition is sodium laureth sulphate 1 EO. The alkyl ether sulphate surfactant is included in 1 to 7.5%, preferably 2 to 6.5% by weight of the composition. The chemical formula of sodium laureth sulphate is CH s(CH 2) n(OCH 2CH 2) _n OSO sNa.

The primary surfactant could alternately be alkyl benzene sulphonate (LAS). The chemical structure of LAS is

LAS for use in the present invention preferably has an alkyl chain having 11 to 14 carbon atoms. Of the two possible surfactants, the preferred primary surfactant is alkyl ether sulphate surfactant. It has been found that inclusion of the primary surfactant is important as it gives cleaning as well as antimicrobial benefits.

The composition of the present invention comprises an alkyl poly glucoside (APG) surfactant. The APG surfactant preferably comprises an alkyl chain having 8 to 15 carbon atoms i.e. it is a alkyl (C8-C15) poly glucoside surfactant. Commerically available APG surfactant of this class are Glucopon 425 N/HH, Glucopon 215 UP, and Glucopon 420 UP. The composition comprises 2 to 4%, preferably 2 to 3.5% APG surfactant by total weight of the composition. It has been found that inclusion of this surfactant is important as it gives cleaning as well as antimicrobial benefits.

The composition comprises an alkyl sulphate surfactant. The alkyl sulphate surfactant for inclusion in the composition of the invention preferably has 10 to 18 carbon atoms, more preferably C10 to C12 carbon atoms. The surfactant has a counterion which is an alkali metal such as sodium or potassium; or an ammoniacal counterion such as monoethanolamine, (MEA) diethanolamine (DEA) or triethanolamine (TEA). Preferably it is sodium or potassium, most preferably it is sodium. The most preferred surfactant of this class for inclusion in the composition of the invention is sodium lauryl sulphate. The alkyl sulphate surfactant is included in 2.5 to 7.5%, preferably 3 to 7%, more preferably 3.5 to 6% by weight of the composition. It has been found that inclusion of this surfactant is important as it gives antimicrobial benefits.

The composition of the invention includes a biodegradable chelating agent. Biodegradable chelating agents are also referred to as green chelating agents. They degrade easier compared to conventional chelating agents in the waste streams after use of the composition in cleaning the dishes in the kitchen. The easier degradability is possible in purely organic chelating agents preferably those that are carboxylic acid or amino acid based. Preferred chelating agents as per the present invention are selected from one or more of sodium gluconate, methyl glycine diacetate (MGDA), L-glutamic acid N, N-diacetic acid sodium (GLDA), sodium citrate, ethylenediamine- N,N'-disuccinic acid (EDDS), Iminodisuccinic acid (IDS), and polyaspartic acid. Of these the more preferred agents are one or more of sodium gluconate, polyaspartic acid, MGDA and GLDA, further more preferred agents are one or both of MGDA and GLDA, most preferably MGDA. The chelating agent is included in 0.5 to 2%, preferably 0.5 to 1.5% by weight of the composition. It has been found that inclusion of this chelating agent is important as it gives antimicrobial as well as sequestering and buffering action.

The composition of the invention includes 0.5 to 1.5% of a C2-C3 phenoxy alcohol. Use of phenoxy ethanol is especially preferred. It may be hypothesized that the phenoxy alcohol is useful in providing antimicrobial as well as preservative benefit.

It is preferred that the composition includes a solvent selected from one or more of a C3 to C8 alkane diol. Preferred alkane diol is one or both of mono propylene glycol (MPG) or octane diol preferably MPG. This solvent is preferably included in 0.1 to 1.5% by weight of the composition. Inclusion of this solvent delivers antimicrobial benefit.

The composition is in liquid form. It contains high amount of water. Water is generally present in 70 to 90%, preferably 75 to 85 % by weight of the composition.

The composition may optionally comprise other ingredients, such as fragrance and/or colour.

The composition preferably has a pH in the range of 9 to 11 preferably in the range of 10 to 11. The formulation is homogenized and the pH of the formulation is directly measured using a precalibrated pH meter.

The composition preferably has a low viscosity which makes it suitable for spraying using a hand held spray pump. The viscosity is preferably in the range of 1 to 100 cps, more preferably in the range of 1 to 10 cps at 25 °C.

The composition of the invention is preferably used for cleaning utensils, surfaces and appliances in the kitchen. Such surfaces may be made from many different materials, including for instance plastics, wood, metal, ceramics, glass, concrete, marble, and painted surfaces. The composition may be applied to the surface by any suitable means known to the skilled person. For instance, a suitable means may be pouring, dropping, spraying or wiping.

In certain vertical surfaces, it may be sprayed on using a hand held spray pump. In certain cases, the compositions after it is applied on to the desired surface, may be wiped off to a substantially dry condition using a dry cloth or wipe.

Another aspect of the present invention relates to a method of disinfecting a surface comprising the step of applying the composition of the present invention on to a surface. The composition may thereafter by wiped off form the surface or may optionally be rinsed off from the surface using copious amounts of water.

The invention shall now be exemplified by the following non-limiting examples.

Examples

Compositions as shown in Table - 1 were prepared.

Table -1 :

In the above compositions the ingredients are as follows:

SLES is Sodium laureth suphate 1EO

APG is Glucopon 215 UP

SLS is sodium lauryl sulphate

MGDA is methyl glycine diacetate

POE is phenoxy ethanol MPG is mono propylene glycol

CAPB is coco amido propyl betaine

All of the above compositions were made in liquid form with the rest of the composition made up to 100% with water.

Each of the compositions were tested for antibacterial kill against S. aureus and P. aeruginosa using the procedure as given below:

7cm x 9cm x 4.5 cm sponges are cut into 6 pieces and they are washed with laundry detergent for 1 hour at 60°C in a washing machine. They are rinsed with distilled water to remove the traces of detergent and then autoclaved at 121 °C for 15 minutes.

Stock bacterial cultures are prepared as per EN 1276 containing 8 log of test bacteria. In a sampling container, to a piece of sponge 1ml mix containing low soil: 0.3% BSA and bacterial culture in a ratio 1 :1 is added. Sponge is squeezed for the equal distribution of bacteria in the sponge.

After 2 minutes of contact time, 4.5 ml of mix containing 2.5ml of 37.5 FH hardwater (EN 1276) 2ml of product was added on the sponge and squeezed.

A contact time time of 4 hours was given.

20ml of neutraliser solution is added into the sample container for neutarlization. After 5 minutes of neutralization time, 1ml of neutralised sample was serially diluted and plated to determine the TVC and Log reduction as per EN1276 protocol.

The antibacterial kill in terms of log reduction is summarized in the table - 2 below:

Table -2 The data in the table -2 above indicates that compositions as per the invention (Examples 1 to 4) is highly efficient in log kill against both gram positive as well as gram negative bacteria as compared to compositions outside the invention (Example A to D).