WO2007054238A1

WO2007054238A1 - Hygiene indicator device

Info

Publication number: WO2007054238A1
Application number: PCT/EP2006/010554
Authority: WO
Inventors: Julie Rosalyn Das; Lorraine Dawn Mcdonald; Philip Michael Ryan; David Richard Ward
Original assignee: Unilever N.V.; Unilever Plc; Hindustan Lever Limited
Priority date: 2005-11-08
Filing date: 2006-11-03
Publication date: 2007-05-18
Also published as: AR056784A1

Abstract

The invention provides a hygiene indicator device for transferring an indicator dye to a hard surface that comprises a first part (the tip) comprising an indicator composition with an anionic dye, and a second part attached to the first part.

Description

HYGIENE INDICATOR DEVICE

Field of the invention

The present invention relates to a hygiene indicator device and methods for applying a hygiene indicator to a hard surface, involving the application of an anionic dye to a composition present on the surface.

Background of the invention Hygiene is traditionally an important factor in hard surface cleaning. Unfortunately a surface that looks clean is not necessarily a hygienic surface, as bacteria, viruses and other germs, are normally not visible to the human eye. It is of high concern to the present day consumers that the hard surfaces in their homes are hygienic, in particular toilets and kitchen and bathroom surfaces.

In WO2005/059162 (Kimberly-Clark) , a microbe sensitive colorant is disclosed, that undergoes a visual change in the presence of a microbe. Although the composition and method as disclosed are very suitable to indicate the presence of microbes at a certain time, the colorant is easily rinsed or wiped away during use of the hard surface or e.g. by flushing of a toilet.

In US2005/0037501 (ECOLAB) another device is disclosed that is aimed at detecting the presence of organic residues on a surface. In this disclosure, the surface is swabbed with an adsorbent stick that comprises an indicator and gives a visual reaction on the stick. Present day hard surface cleaning compositions often comprise additional components in order to not only clean but also disinfect the surface for an extended period of time. It is also known in the art that certain components such as quaternary ammonium compounds and bis (2- hydroxyethyl) alkylamines (e.g. Ethomene, trade-mark ex Akzo) have the ability to stick to a hard surface such as a toilet bowl as disclosed in EP1025191 and co-pending European application number 05250898. They are described to contribute to disinfection.

Also known in the art, are cleaning compositions comprising a dye, to indicate the presence of e.g. protein residues. Such a system can be found in WO93/19152, which discloses an aqueous cleaning composition comprising dye, preferably an acid dye, which is substantive to protein. The dye can bind to protein to form a visible coloured complex and so reveal soil. By visualising protein, soil can be targeted for cleaning. Any dye remaining visible after cleaning indicates imperfect cleaning.

An indicator that can be applied to the hard surface and shows the presence of the retained cationic hygiene agent on the surface for an extended period of time remains to be desired.

Summary of the invention

It has now been found that anionic dyes can be used to indicate the presence of a cationic hygiene agent, thus indirectly indicating hygiene. Thus the present invention provides a hygiene indicator device to apply an anionic dye to a hard surface.

The invention further provides a method for transferring the dye to the hard surface, utilising the device of the invention.

Furthermore the invention provides a method for indicating hygiene on a hard surface utilising the device of the invention and the method for transferring the dye.

The dye is a water-soluble dye that can interact with the cationic hygiene agent on the target surface. By forming a water insoluble reaction product the dye leaves a coloured residue which is resistant to rinsing and thus discloses the presence of the hygiene agent, even after repeated rinsing. It is important that the reaction is specific to the targeted hygiene agent .

Detailed description

All percentages mentioned herein are by weight based on the total composition, unless specified otherwise.

Accordingly, the present invention provides a hygiene indicator device for transferring an indicator dye to a hard surface comprising at least one part, which comprises an indicator composition. The indicator composition comprises at least an anionic dye. The composition may optionally comprise further ingredients.

The invention also provides a method for transferring an anionic dye to a hard surface comprising the step of touching the hard surface with at least part of the indicator device of the invention in the presence of a solvent .

The invention further provides a method for indicating the presence of a cationic hygiene agent on a hard surface, comprising the steps of treating a surface with a cationic hygiene agent and applying the anionic dye to the surface according to the method above .

For the purpose of the invention a cationic hygiene agent is a compound which comprises a group carrying a positively charge when in contact with water of sufficiently low pH and which has biocidal activity.

This includes compounds which inherently carry a positive charged group, such as organic quaternary ammonium salts an compounds that are protonated at sufficiently low pH, such as organic amines .

For the purpose of the invention, with biocidal activity is meant all activity that leads to: full or partial microbial growth inhibition, microbial growth rate reduction and/or full or partial killing of the microbes, wherein microbes may include amongst others bacteria, virusses and funghi .

Hygiene indicator device

The hygiene indicator device may comprise of one or more parts .

In any configuration, at least one part (hereinafter referred to as "the tip") of the device comprises the indicator composition including an anionic dye as defined herein below. The anionic dye may be present on the whole device. However, particularly when the indicator composition is present on the device in liquid form, this may lead to contamination of the hands of the user of the device. Therefore, in a preferred embodiment only the tip of the device comprises the indicator composition, whereas the part intended to be held by the user does not contain the indicator composition.

The parts of the hygiene indicator device, i.e. the tip and optionally a second part intended to be hand-held, may be separate members or constructed as one unified device. They may or may not be made of the same material .

In a preferred embodiment, the two parts of the device are separately made and thereafter put together. More preferably, the device is elongated, with one end intended to be hand-held and the other end comprising the indicator composition. The hand-held part may be constructed of any solid material, the only proviso being that it is compatible with the human skin.

The hygiene indicator device is preferably constructed of biodegradable materials. Even more preferred the indicator device be constructed from materials that disintegrate on prolonged contact with water, thus making it suitable to be easily disposed of, e.g. by flushing through a toilet.

The tip is preferably made of absorbent carrier material. Any hydrophilic absorbent material is suitable. Examples of absorbent materials are: woven or non-woven fabric of natural or synthetic fibres such as wool, cotton, paper, acrylic, flax, cellulose acetate, jute, felt, polyester, polyamide and/or polyolefin fibres, including substituted polyolefines, such as polyvinylidene difluoride (PVDF) . Cellulose fibre material such as cotton and paper is particularly suitable.

In another preferred embodiment the two parts of the device are integrated on one piece of absorbent material, on which one part comprises the indicator composition comprising the anionic dye and the rest of the piece is not comprising said indicator composition, and is intended to be handheld.

Indicator composition

For the purpose of this invention an anionic dye is defined as a compound having a visible colour and being able to bind to a cationic hygiene agent that is bound to a surface. The binding of the anionic dye to the cationic hygiene agent may be by covalent bond, ionic binding, Van der Waals binding, dipole-dipole-interaction, hydrogen bond, or combinations thereof.

Dyes are described in Industrial Dyes (K. Hunger ed, Wiley- VCH 2003) . A compilation of available dyes is the Colour Index published by Society of Dyer and Colourists and American Association of Textile Chemists and Colorists 2002 (see http://www.colour-index.org) .

Suitable anionic dyes for the current application may be taken from any of the chromophore types, e.g. azo, anthraquinone, triarylmethane, methine quinophthalone, azine, oxazine thiazine, xanthene, porphyrin, phthalocyanin .

The anionic dye is preferably an acid dye. Acid dyes generally are soluble in water and are not strongly substantive to the carrier materials described above.

Preferably the dye contains 1 or 2 negatively charged groups at suitably high pH.

A preferred sub-class of the acid dyes of the invention are dyes of the xanthene dye type, particularly based on the structure :

where the dye may be substituted by halogens, methoxy, ethoxy, nitro, alkyl or amine groups. The counter ions may be hydrogen, ammonium, potassium or sodium.

Xanthene dyes include acid yellow 73, acid orange 11, acid red 98, acid red 92.

Especially preferred anionic xanthene dyes are Erythrosin B and Eosin YS or YSK, or combinations thereof.

Preferred dyes are those which provide a colour to the hard surface such that the hue angle, h, in the CIELAB system of the colour is between 200° and 45°. A detailed description of hue angle may be found on p57 of Color Chemistry, 3^rd edition by H. Zollinger published by Wiley-VCH. The preferred dyes are blue, red or violet.

To avoid degradation by light it is preferred that at least the part of the device comprising the composition is protected from light during storage.

The following two lists of dyes are illustrative of the materials that could be used to indicate the presence of these cationic hygiene agents. The dyes in List 1 generally give stronger colouring than the dyes in List 2.

List 1 Acid Blue 7 (also known as CI 42080,

Erythrosin B (also known as CI 45430, or Acid Red 51 or

E127) ,

Eosin YS or YSK (also known as CI 45380 or Acid Red 87) ,

Food Red 1 (also known as CI 14700 or Ponceau SX) Acid Red 17 (also known as CI 16180)

Acid Red 88 (also known as CI 15620)

Bromothymol Blue

Bromo phenol Blue

Rose Bengal

List 2

Acid blue 3 (also known as Patent blue V, E131 or CI 42051)

Food black 1 (also known as CI 28440)

Acid Red 27 (also known as Food Red 9, Amaranth or CI 16185)

Acid Blue 80 (also known as CI 61585)

Acid Blue 62 (also known as CI 62045) Acid red 1 (also known as CI 18050)

Ext. D&C violet 2 (acid violet 43)

Acid blue 9 (also known as Alphazurine FG or CI 42090)

These lists are showing examples of suitable dyes and are by no means exhaustive. The dyes of List 1, are generally preferred as they give stronger colouring than the dyes of list 2.

Selectivity

For the purpose of the invention, it is preferred that the anionic dye of the invention is selective in indicating the cationic hygiene agent. Dyes that will also react with protein, or microbes may not be preferred for all application purposes since they may lead to "false positive" indications. Examples of such dyes are Bromothymol Blue and Rose Bengal, from List 1.

Other dyes that are used for revealing proteins, such as Coomassie (a.k.a. Brilliant blue R) are also not preferred.

Polysulphonated acid dyes are less suitable for the purpose of the invention as the "complexes" they form with a cationic agent are very soluble in water and therefore easily washed away.

In order to be safe for use by the average consumer, the anionic dye should be biodegradable and harmless to the skin and preferably on the European approved list of dyes for cosmetics and food use (directive 76/768/EEC Annex IV part 1) . Further components

The indicator composition may further comprise pH regulating acids, bases or buffers, a stabiliser for the dye and/or a solvent such as water.

Some surfactants may aid dissolution of the dye but will also potentially dissolve the complex of the cationic agent and the anionic dye. Surfactants dissolving the complex are not preferred in the composition.

The pH of the indicator composition may be either acidic, neutral or alkaline. If it is desired that the indicator is able to specifically detect quaternary ammonium hygiene agents and not detect molecules that only are cationic at low pH it is preferred that the indicator composition is alkaline or slightly acidic.

One of the preferred groups of cationic hygiene agents are quaternary ammonium compounds (RiR₂RaI^iN⁺ X^") , such as Cetyl- trimethylammonium chloride.

For good binding of the anionic dye to these hygiene agents, the indicator composition preferably has a pH at or below 9 and a pH at or above 4.

Other preferred cationics which have been shown to deliver a hygiene benefit are bis (2-hydroxyethyl) alkylamines (available commercially from Akzo as Ethomene™) For good binding of the anionic dye to those compounds, the indicator composition preferably has a pH of < 7 Thus, the indicator device can be made to selectively indicate the presence of quaternary ammonium hygiene agents by ensuring that the pH of the area of contact between the tip and the surface to be tested is alkaline.

Application method

The indicator device is particularly suitable for indicating the presence of a cationic hygiene agent on a surface. Such agents are used in various hard surface cleaning compositions, but it will be normally be unknown to the consumer whether, some time after cleaning, such agent is still present on the surface to perform its hygiene function. By applying an anionic dye to the surface with the indicator device of the invention, the consumer can test whether the agent is still present. The continued presence of the dye on the surface, after rinsing, signals to the consumer that the hygiene agent is still present.

The indicator composition comprising an anionic dye and other components mentioned above may be present on the tip either in solution or as solids. Wet tips are particularly suitable to be used on dry surfaces, whereas on a wet surface wet or dry tips can be used.

For the purpose of this invention wet means "in the presence of a solvent" . The solvent is preferably an aqueous solvent . The solvent can be present in the indicator composition or on the surface to be tested or both. The solvent optionally comprises further components to adjust or control the pH. Organic solvents may aid dissolution of the dye but may also potentially dissolve the complex of the cationic agent and the anionic dye and are therefore preferably not present in the composition.

As briefly indicated above and without wishing to be bound to a theory, the reasons for using the indicator device are further set out below.

When a household cleaning composition comprising a cationic hygiene agent is applied to the surface, a film of agent may be left on the surface. The agent will be gradually washed away at subsequent and repeated rinsing of the surface. It is usually unclear whether after some rinsing the hygiene agent is still present or not.

The invention is particularly useful to indicate the presence of a hygiene agent on a toilet surface, such as the inside of the toilet bowl.

Accordingly, in a preferred embodiment the present invention provides a method for transferring a dye to a hard surface comprising the step of touching the hard surface with the tip of the indicator device according to the invention in the presence of water or an aqueous solution. Preferably the hard surface is a toilet surface.

The invention further provides a method for indicating the presence of a cationic hygiene agent on a hard surface, comprising the steps of cleaning a surface with a cationic agent, applying the anionic dye to the surface using the device of the invention and followed by disposing of the device .

The invention further provides the use of the indicator device to reveal the presence of a cationic agent on a hard surface .

In order to be disposable by regular household ways (e.g. garbage bin disposal or flushing through the toilet) , the indication device and composition are preferably biodegradable .

The invention also provides a kit comprising a composition comprising a cationic agent, preferably a cationic biocide; and the indicator device of the invention.

Examples

The invention will now be illustrated by way of the following non-limiting examples, in which all parts and percentages are by weight unless otherwise indicated.

For reasons of test convenience, the device used in some of the examples consists of one-part, the tip only. However, it should be understood that two-part devices as described above are also included in the scope of the inventions.

Example 1 - Mode of action of the indicator device. A model bleach formulation is prepared according to the composition shown in table 1. Table 1

The bleach formulation is applied to a toilet surface and allowed to dry for at least 3 hours to simulate household practice in toilet cleaning. The toilet is then flushed at least twice (and up to 25 times) using a standard flush from a 6 litres capacity cistern, allowing the toilet cistern to refill completely before flushing again.

An indicator device is prepared by treating a 2 cm square of soft paper with 50 microlitres of a 2.5% aqueous solution of erythrosin B. The paper is allowed to dry fully.

The test device is then placed on the flushed wet toilet surface above the water line and allowed to absorb residual water from the surface. The device is then removed from the surface by flushing the toilet. The presence of residual CTAC is revealed by the presence of a clear pink stain where the device has contacted the surface.

Example 2 - Effect of dye structure on the efficiency of the feedback device A series of indicator devices are prepared by treating paper squares as indicated in example 1 with 2.0% solutions of the following dyes in water.

Dye 1 Acid red 88 (CI 15620)

Dye 2 Acid red 17 (CI 16180)

Dye 3 Acid red 27 (CI 18050)

The paper is dipped into the dye solution and allowed to dry. A toilet surface was treated with the model bleach product as described in example 1 and flushed twice. A sample of paper treated with each of the dyes was contacted with a wet area of the surface and the toilet was then flushed. Where the indicator treated with dye 3 was contacted with the surface very little staining occurred because the multiple sulphonate groups cause the complex of the dye with CTAC to be too soluble to leave a permanent residue. Dye 1 gives the strongest coloured stain and dye 2 gives a slightly weaker colour.

This example shows that the dye structure has an effect on the solubility of the complex and that is useful to balance the water solubility of the dye to ensure rapid dye transfer while minimising the solubility of the resulting cation-dye complex.

Example 3 - Illustration of alternative carrier material and dye on the indicator device

A 1% solution of Acid Blue 7 was prepared in aqueous ethanol (50:50%) . A 25 mm diameter polyvinylidene difluoride (PVDF) filter disk ex Millipore with 5 micron porosity was dipped into the solution and dried. A toilet was treated with the product described in example 1 and allowed to dry for 5 hours before flushing 10 times. The indicator device was applied to a wet area of the surface and then the toilet was flushed. A blue stain was transferred to the toilet indicating the presence of the cationic hygiene agent. Example 4 Optimisation of the feedback device for the detection of CTAC while excluding Ethomene .

A solution of model bleach was prepared as described in example 1 above. A solution of a model acid based toilet cleaner was prepared according to the composition in table 2

Table 2

A series of solutions were made up using 2.5% Erythrosin and a range of sodium carbonate concentrations (0.05, 0.16, 0.3125, 0.625, 1.25 and 2.5%) . 50 microlitres of each of these solutions was applied to two 25 mm diameter polyvinylidene difluoride filter disks ex Millipore (5 micron porosity) and the disks were allowed to dry.

A white ceramic tile surface was treated with the model bleach sample described in example 1 above. A second tile was treated with the model acid based cleaner described in table 2. The tiles were allowed to drain and dry for 3 hours before being placed in a rinsing device that allows a constant flow of water to drain across the entire surface of a pair of tiles. The flow rate is set at approximately 10 litres per minute across a weir which covers the entire width of the two tiles (approximately 260 mm) to simulate the flow encountered in a flushing toilet . The two treated tiles were rinsed for 2 minutes. After this rinsing each indicator paper was moistened with water (50 microlitres) and one of each was placed on the two tiles. After 20 seconds contact time the indicator devices were removed to show clear stained areas. The tiles were then flushed for 20 seconds to remove any excess dye.

This test showed that as the carbonate level in the indicator device was increased the amount of dye transferring to the surface was reduced for both the Ethomene and CTAC containing products but the effect on the CTAC containing product was only small. At all concentrations the CTAC tile showed a clear residue indicating that the CTAC remained on the surface. At a loading of 1.25% sodium carbonate and above there was no dye complex formed on the tile treated with the Ethomene containing product. This indicates that while CTAC and

Ethomene are both detected by complex formation between the cationic forms of these materials increasing the pH forces the actives into less ionic form and reduces the ability to complex with the dye. By careful control of the amount of base present the indicator device can be tuned to detect only the presence of the quaternary ammonium compound.

Example 5 - Different modes of application.

A ceramic toilet was treated with the formulation described in example 1 above by applying approximately 60 ml of product evenly around the bowl under the rim. The product was allowed to drain and dry overnight . Indicator devices

Solutions of dye were prepared using the following materials: Erythrosin, Acid Blue 7, and bromophenol blue all made up to approximately 2% dye in aqueous ethanol . Each of these solutions was applied to a small number of 25 mm diameter polyvinylidene difluoride (PVDF) filter disks ex Millipore (5 micron porosity) by dipping the disks in the solution and the disks were allowed to dry.

The toilet was flushed twice allowing time for the cistern to refill completely between flushes. The cistern capacity was set to deliver 6 litres of water per flush. While the surface was still wet an erythrosin dyed disk was placed on the rear surface of the toilet bowl above the water line. Once the cistern had refilled the toilet was flushed again to wash away the device and reveal a red stain where the indicator device had been positioned, indicating the hygiene agent. The toilet was flushed for a fourth time and the presence of residues was tested using an acid blue dyed disk. This was placed on the surface of the toilet bowl next to the original stained area. The toilet was flushed for a fifth time to reveal a blue stained area where this disk had been placed. The red stain previously revealed remained. This process was repeated with the placement of a Bromophenol blue disk after 6 flushes, an Erythrosin disk after 9 flushes and again after 12 flushes, a Bromophenol blue disk after 15 flushes, an Erythrosin disk after 17 flushes, an Acid Blue disk after 20 flushes and finally an Erythrosin disk after 25 flushes, all indicating the presence of the cationic hygiene agent. In all cases the area where the disks had been applied showed a clear transfer of blue or red staining depending on the dye used. All the previously stained areas were clearly visible after the 25 flushes although the blue stains showed some signs of fading with repeated flushes. This fading was less noticeable with the Erythrosin treated areas indicating that this stain is more resistant to further rinsing.

After the 26^th flush the toilet which now had numerous stained areas was treated with the neat bleach product by applying approximately 60 ml around the bowl under the rim. The level of surfactant in this formulation is sufficient to solubilise the dye complexes formed on the surface and when the toilet was flushed again the stains washed away with the flush water.

The indicator device was applied to a wet area of the surface and then the toilet was flushed. A blue stain was transferred to the toilet indicating the presence of the cationic hygiene agent.

This experiment demonstrates the longevity of the surface treatment, the sensitivity of the different dyes to the remaining residue and possibly counter- intuitively the ease of removal of the stains simply by using the product that left the residues in the first place.

Example 6 - False Positives.

As the indicator preferably should not show microbial matter, also referred to as "false positives", various dyes were tested for indication of the presence of bacteria. 17 dyes were tested:

Acid Blue 7 Bromothymol blue Duramine Red

Acid Blue 80 Acid red 27 Acid blue 3

Food Black 1 Patent blue V Acid blue 9 Rose Bengal D&C violet no2 Food red 1

Eosin Acid red 88 Bromophenol blue

Telson blue Acid Red 17

Test method A small amount of dye was dissolved in approximately 5 ml deionised water (no carbonate was added) .

Tiles with microbial matter were prepared in two ways. A thin layer was prepared by applying 100 microliter containing 10e6 cfu/ml E. coli onto clean ceramic tiles and allowed to dry for 5 hours. And similarly a thicker layer was prepared by applying 50 microliter containing 10e8 cfu/ml E. coli onto clean ceramic tiles and allowed to dry for 5 hours.

Escherichia coli (or E. coli) is a Gram-negative bacterium from the family Enterobacteriacae. As E. coli is a normal inhabitant of the human intestines and a common cause of gastrointestinal diseases, it is a suitable bacterial test strain for toilet hygiene.

Approx 0.5 - 1 ml dye solution was pipetted onto the dried bacterial film and left for 30 sees. Then the dye was rinsed away with deionised water from a wash bottle. Results :

Only one of the tested dyes (Acid red 17) showed some colour on the bacterial film, although it only stained the thicker layers of the dried film, but was not substantive to the tile and was rinsed away along with the stained film. The other dyes did not show staining.

Claims

A hygiene indicator device for transferring an indicator dye to a hard surface comprising a first part (the tip) comprising an indicator composition which comprises an anionic dye.

A hygiene indicator device according to claim 1, wherein the device further comprises a second part (the hand-held part) attached to the first part.

An indicator device according to any one of claims 1 or 2, wherein the indicator device is biodegradable.

An indicator device according to claims 1 to 3 , wherein the anionic dye is an acid dye.

An indicator device according to anyone of claims 1 to

4, wherein the acid dye is a xanthene dye.

An indicator device according to anyone of claims 1 to

5, wherein the xanthene dye is Erythrosin B and/or Eosin YS or YSK, or combinations thereof.

An indicator device according to anyone of claims 1 to

6, wherein the tip comprising an indicator composition further comprises one or more pH regulating acids, bases or buffers, stabilisers for the dye and/or solvents. An indicator device according to anyone of claims 1 to

7, wherein the two parts of the device are integrated in one piece of absorbent material, of which one part comprises the composition comprising the anionic dye and the other part does not comprise the composition.

An indicator device according to anyone of claims 1 to

8, wherein the two parts of the device are integrated on one piece of absorbent material .

An indicator device according to anyone of claims 1 to 8, wherein the tip is made of adsorbent material and the hand-held part is an elongated member.

An indicator device according to anyone of claims 1 to 10, wherein the indicator composition has a pH at or below 9.

A method for transferring a dye to a hard surface comprising the step of:

(a) Touching the hard surface with the tip of the indicator device according to anyone of claims 1 to 11 in the presence of a solvent.

A method for transferring a dye to a hard surface according to claim 12, characterised in that the hard surface is a toilet surface. A method for indicating the presence of a cationic hygiene agent on a hard surface, comprising the step of transferring the anionic dye to the surface according to the method of claim 12 by touching the surface with the tip of the device of claims 1 to 11 in the presence of a solvent.

Use of the indicator device according to any one of claims 1 to 11 to reveal the presence of a cationic agent on a hard surface .

Kit of part comprising:

(a) the indicator device according to any one of claims 1 to 11; and

(b) a composition comprising cationic agent.