WO2019072349A1

WO2019072349A1 - Antimicrobial cloth

Info

Publication number: WO2019072349A1
Application number: PCT/DK2018/050254
Authority: WO
Inventors: Torben Holm LARSEN
Original assignee: Real Relief Holding Aps
Priority date: 2017-10-12
Filing date: 2018-10-12
Publication date: 2019-04-18
Also published as: EP3694328A1

Abstract

The present invention relates to an antimicrobial cloth comprising a microfiber substrate with an antimicrobial functionalisation. The antimicrobial cloth is useful for the cleaning of hands.

Description

Title of the invention

Antimicrobial cloth

The present invention relates to an antimicrobial cloth and a method of reducing microbes on a surface using an antimicrobial cloth.

Background

It has long been understood that regular cleaning is important to ensure that harmful microbes are destroyed. This is particularly important for personal hygiene, especially for the hands. Hands are regularly exposed to microbes, which if not dealt with, can accumulate and be ingested which can lead to illness or even death.

Typically, the hands are washed using either a solid soap bar or a liquid formulation and creating a lather with water. The hands are then rinsed and dried. However, water is not always readily accessible and it can therefore be difficult to sanitise the hands in the absence of sufficient water resources. This is a significant problem in countries in which water supplies are scarce and access to clean water is limited. It is also a problem in situations where the hands need to be washed but there is no clean water supply nearby. This may be applicable, for example, during emergencies like flooding, earthquakes, war zones or when camping or participating in other outdoor activities.

Solutions have been proposed which do not rely on a water source, including for example alcohol-based hand sanitisers. These simply involve dispensing an alcohol-based formulation onto the hands, dispersing appropriately and allowing the formulation to evaporate. Microbes are killed by the formulation before it evaporates. Whilst this solves the problem of sanitising the hands in circumstances in which water is not accessible, there are problems associated with using alcohol-based hand sanitisers. Firstly, they are expensive and therefore generally not suitable for use in poor countries which do not have access to clean water. Secondly, they are bulky and therefore not easy to distribute to remote areas. Distribution of such items is expensive. Thirdly, they can dry out the skin leading to discomfort or even more serious skin conditions.

Wet-wipes also provide an alternative means of sanitising the hands without the need for water. However, it would be expensive to use wet wipes every time the hands need to be cleaned and so this is also problematic for use in countries where access to clean water is an issue. Also, the disposable nature of wet wipes means that it would be harmful to the environment if wet- wipes were used widely for hand sanitation.

There is a need for an alternative means for sanitation which overcome some or all of the drawbacks of these conventional systems.

Recently, an antimicrobial sanitary pad has been developed for use by women to absorb bodily fluids released during their menstrual period. The pad has an antimicrobial top layer, an absorbent middle layer and a bottom layer which helps to prevent leakages. The top layer comes into contact with the body during use and has an antimicrobial coating comprising a nitrogen atom attached to a carbon chain.

The coating has been found to be effective against a variety of bacteria including Staphylococcus Aureus, Klebsiella Pneumoniae, Escherichia Coli, Candida Albicans, Pseudomonas Aeruginosa, and Aspergillus Niger. It therefore helps to reduce the risk of vaginal infections caused by such bacteria.

However, the antimicrobial sanitary pad is intended to operate in a moist environment and at a temperature and pH affected by the bodily fluids it absorbs. The absorbent layer beneath the top layer absorbs fluid from the body and holds it away from the body until the pad is replaced.

Sanitation means used when cleaning the hands have a contact time of typically up to about a minute. Thus, the majority of microbes need to be killed within this short period of time, or at least captured quickly to subse- quently be killed after removal from a surface such as the hands. Further, a hand-washing cloth would not be in contact with the hands for sufficient time for there to be any significant warming from the body.

Summary of Invention

It is an object of the present invention to provide an antimicrobial cloth that can be used to reduce the number of microbes in situations where access to water is limited, but which overcomes at least one of the disadvantages of conventional solutions. Thus, according to a first aspect of the present invention there is provided an antimicrobial cloth comprising a microfiber substrate having an upper and a lower surface, the substrate comprising an antimicrobial functionalisation in an antimicrobial region, the antimicrobial region being on the upper surface and/or the lower surface, the antimicrobial functionalisation comprising linking sections joined to active sections and to the substrate in the antimicrobial region,

the linking sections having a structure according to Formula I, wherein Formula I is:

Formula I: -0-Si-(CH₂)_n- wherein n is an integer in the range from 1 to 15

and further wherein, optionally, one or more hydrogens of the linking section is substituted with a halogen atom or a straight or branched alkyl group having from 1 to 10 carbon atoms;

the active sections having a structure according to Formula II, wherein

Formula II is:

Formula II: -N⁺R¹ R²R³

wherein R¹ is selected from alkyl chains having a backbone of from 4 to 30 carbon atoms, wherein one or more hydrogen atoms may be substituted with a halogen atom or a straight or branched alkyl group having from 1 to 10 carbon atoms, wherein one or more hydrogens on the straight or branched alkyl group having from 1 to 10 carbon atoms may be substituted with a halogen atom;

and wherein R² and R³ are each independently selected from alkyl chains having a backbone of from 1 to 30 carbon atoms, wherein one or more hydrogen atoms may be substituted with a halogen atom or a straight or branched alkyl group having from 1 to 10 carbon atoms, wherein one or more hydrogens on the straight or branched alkyl group having from 1 to 10 carbon atoms may be substituted with a halogen atom and wherein the microfiber sub- strate comprises filaments of 1 denier or less.

Preferably, the linking sections are covalently joined to the active sections via a C-N bond. Preferably the linking sections are also covalently joined to the substrate via an X - O - Si linkage, wherein X is an atom of the substrate, for example carbon.

It has surprisingly been found that the antimicrobial cloth of the present invention can be used for sanitation of, for example, the hands, even when there is very little water available, and in particular it has been found that the sanitisation occurs even though the water used contains microbes. Traditional washing of hands, or other surfaces, involves using a surfactant, e.g. a bar of soap, to release the microbes from the surface so that the released microbes can be flushed away using water, which must necessarily not contain microbes for the sanitisation to work. In contrast, the antimicrobial cloth kills microbes present in water used with the antimicrobial cloth, and therefore the present invention allows handwashing to be performed in dirty water.

Moreover, sanitisation using the antimicrobial cloth of the invention can be achieved using much less water than a traditional wash using soap and water. For example, the World Health Organization (WHO) explains in its bro- chure Hand Hygiene: Why, How & When? (August 2009) that during handwashing the hands must first be wetted and then, after applying and distributing soap, rinsed with water. While the water need not be running for the full duration of the handwashing procedure (40 to 60 seconds according to the WHO) the consumption of water will be larger than the 50 ml typically applied with an an- timicrobial cloth of the invention (e.g. a cloth having size of 25 cm x 25 cm will typically be fully wetted with 50 ml of water), and an antimicrobial cloth of the invention of this size is adequate for replacing handwashing.

The antimicrobial functionalisation provides effective antimicrobial properties. Without wishing to be bound by any theory, it is believed that in use the nitrogen atoms are positively charged thereby attracting microbes. The al- kyl chains of the active sections, and possibly the linking sections, intercept and kill the attracted microbes. In particular, the antimicrobial functionalisation of the antimicrobial cloth will also attract and kill the attracted microbes present in water used with the antimicrobial cloth, so that a surface can be sanitised using water containing microbes. The present inventor further contemplates that any moisture, e.g. sweat, naturally present on the hands or another surface of a human being or another animal may be sufficient for activating the attrac- tive forces, where necessary, between the nitrogen atom and the negative surface of a microbe so that the microbe is attracted to the antimicrobial function- alisation.

After use, the cloth can be rinsed without deterioration of the antimicro- bial properties and is therefore reusable many times over. The cloth is self- sterilising and so can be rinsed in cold, unclean water. Thus, the cloth is particularly suitable for use in situations where there is little or no access to clean water. The reusable nature of the cloth means that the cost over the lifetime of the product is significantly less than alternative options. Also, since the cloth is reusable rather than disposable, it carries a smaller environmental cost than alternative disposable options. Furthermore, the antimicrobial cloth, as opposed to most other hand sanitising methods, does not leave any antimicrobial substances, like alcohol or silver ions on the surface, e.g. the hands of a user. In a specific embodiment, the antimicrobial cloth does not comprise silver ions. In a further embodiment, the antimicrobial cloth does not comprise alcohol, e.g. ethanol. It is preferred that the antimicrobial cloth is used without alcohol, e.g. ethanol. Commonly used antimicrobial substances, such as ethanol, can be detrimental to the skin of a person, e.g. a doctor or a nurse, who needs saniti- sation at regular intervals. This, the antimicrobial cloth removes the risk of ad- verse reactions, e.g. dry skin, otherwise caused by ethanol.

The antimicrobial cloth is moreover logistically advantageous, since it is less bulky during transportation and storage. For example, present procedures for furthering personal hygiene, especially in distant areas, commonly involves bringing soap, e.g. as bars of soap in large quantities, to families in need. The large quantities of soap are bulky and require storage, but by replacing the soap with the antimicrobial cloth, more people can be reached for the same amount of money. Furthermore, the antimicrobial cloth will typically last longer than commonly distributed bars of soap so that the frequency of distribution can be reduced.

When both the upper and lower surface of the substrate have an antimicrobial functionalisation, the cloth will be particularly effective at sanitising two or more surfaces simultaneously. For example, the cloth may be held in the user's hands, with the upper surface reducing microbes on one hand and the lower surface killing microbes on the other. Likewise, when another surface is sanitised using an antimicrobial cloth having the antimicrobial functionalisa- tion on both the upper surface and the lower surface the sanitising effect will occur both on the hand using the antimicrobial cloth and the surface being san- itised. This is especially relevant since cross-contamination between the hand and the surface is avoided. Thereby, an antimicrobial cloth having the antimicrobial functionalisation on both the upper surface and the lower surface may be used for cleaning another person, e.g. a patient, with a reduced risk of cross- contamination between the person using the antimicrobial cloth and the other person.

The use of a microfiber substrate in which the filaments are 1 denier or less has been found to be particularly effective. Without wishing to be bound by any theory, it is believed that the microfiber substrate can interact with microbes on a surface, thereby removing them from the surface and onto the cloth. Once on the cloth, the active sections interact with the microbes in the manner discussed above to inactivate or kill them. It has surprisingly been found that cloths which do not use a microfiber substrate are significantly less effective at sterilising a surface. This is believed to be because other cloth types are only able to remove significantly fewer microbes from a surface than the cloths of the present invention. The antimicrobial cloths of the present invention have been found to be effective both at removing bacteria from a surface and subsequently inactivating or killing the bacteria transferred from the surface to the cloth.

Without wishing to be bound by any theory, it is believed that the hy- drophobic nature of the active section contributes to the killing of attracted microbes. Any suitable structure for the active section may be used. For example:

In some embodiments, R² and R³ are both , methyl or ethyl groups and R¹ is an unsubstituted alkyl chain having a backbone of from 4 to 20 carbon atoms or from 4 to 10 carbon atoms, or from 10 to 20 carbon atoms or from 6 to 8 carbon atoms. These embodiments are particularly effective as the nitrogen atom is sufficiently exposed to attract microbes i.e. there is not too much steric hindrance, whilst the active sections ensure that microbes are intercepted and killed. In some embodiments, R² and R³ are both, methyl or ethyl groups and R¹ is a branched alkyi chain having a backbone of from 4 to 20 carbon atoms or from 4 to 10 carbon atoms or, from 10 to 20 carbon atoms or from 6 to 8 carbon atoms. In some embodiments, there is a single branch selected from methyl, ethyl, propyl, butyl and pentyl. In other embodiments, there are two or more branches, with each branching group being independently selected from methyl, ethyl, propyl, butyl and pentyl groups. These embodiments are particularly effective as the branching groups contribute to the hydrophobicity of the R¹ group and thereby assist with killing microbes, whilst not being too sterically hindering.

In some embodiments, R² and R³ are both, methyl or ethyl groups and R¹ is an alkyi chain having a backbone of from 4 to 20 carbon atoms or from 4 to 10 carbon atoms, or from 10 to 20 carbon atoms or from 6 to 8 carbon atoms. Any number, e.g. one, two, or three, of the hydrogen atoms of R¹ may be re- placed by a halogen atom, in particular a fluorine atom. These embodiments are particularly effective as the halogen atom, in particular the fluorine atom, modifies the electronic properties of the R group which can in turn modify the way in which the active section interacts with microbes.

In some embodiments, R² and R³ are each independently an unsubsti- tuted alkyi group having from 1 to 5 carbon atoms. R¹ is an unsubstituted alkyi group having from 4 to 10 carbon atoms or from 10 to 20 carbon atoms. For example, R¹ may have 8 carbon atoms and R² may be a methyl, ethyl, propyl, butyl or pentyl group. These embodiments are particularly effective as the R¹ group has effective antimicrobial properties and the R² and R³ groups may pro- vide additional steric hindrance around the nitrogen atom, thereby acting as a shield and preventing attracted microbes from getting too close to the nitrogen atom whilst helping to ensure the microbes are killed.

In some embodiments, R² and R³ are each independently an unsubstituted alkyi group having from 1 to 5 carbon atoms. R¹ is a branched alkyi chain having a backbone of from 4 to 20 carbon atoms or from 4 to 10 carbon atoms or from 6 to 8 carbon atoms. In some embodiments, there is a single branch selected from methyl, ethyl, propyl, butyl and pentyl. In other embodiments, there are two or more two or more branches, with each branching group being independently selected from methyl, ethyl, propyl, butyl and pentyl groups. These embodiments are particularly effective as the branching groups contribute to the hydrophobicity of the R¹ group and thereby assist with killing microbes, whilst not being too sterically hindering. The embodiments benefit from the hydrophobicity of the R¹ group and the shielding effect of the R² and R³ group.

In some embodiments, R¹ ,R², and/or R³ are the same. This can simplify the manufacturing process of the antimicrobial cloth since less control is needed over the formation of the active sections compared to the situation when the R groups are different.

R groups may be connected to form a ring. In this case, a nitrogen- containing ring would be formed. The term "backbone" then refers to the number of carbon atoms that form the ring.

The alkyl groups of R¹ , R² and/or R³ may be connected with other groups, for example other alkyl groups, via any suitable linkage. For example, an ether linkage may be used, or groups may be connected by double or triple carbon to carbon bonds.

It will be understood that one or more substituted or unsubstituted aromatic groups may additionally be included in R¹ and/or R² and/or R³. However, it is preferred that none of the R groups contain an aromatic group.

Quaternary amines are particularly useful since the active section will retain the positive charge even at relatively high pH. Thus, when the active section is according to the present invention the antimicrobial cloth may be used at a pH above 6, in particular in the range of 6 to 8.

In some embodiments, R¹ is an unsubstituted alkyl group having from

4 to 10 carbon atoms or from 10 to 20 carbon atoms and R³ and R⁴ are each independently selected from unsubstituted alkyl groups having 1 to 5 atoms. For example, R¹ may have 8 or 18 carbon atoms and R³ and R⁴ may independently be a methyl, ethyl, propyl, butyl or pentyl group. Optionally, R³ and R⁴ will be the same.

These embodiments are particularly effective as the R¹ group has effective antimicrobial properties and the R³ and R⁴ groups provides additional steric hindrance around the nitrogen atom, thereby acting as a shield and preventing attracted microbes from getting too close to the nitrogen atom whilst helping to ensure the microbes are killed. The permanent charge on the nitrogen atom provides high attractiveness to microbes.

R³ and R⁴ may be independently selected from the same group as R².

It will be understood that the active sections may all have the same structure. Alternatively, there may be two or more different forms of the active sections, with each form having a different structure.

When there are two or more different forms of the active sections, these may be arranged in any suitable way. For example, there may be an alternating pattern in which different forms of the active section are used at regular intervals. Alternatively, the active sections may be grouped so that all of the sections of the same form are together. Where the different forms are grouped together in this way, different regions of the cloth may have different properties.

When both the upper and lower surface of the cloth have an antimicrobial functionalisation, the upper surface may have the same functionalisation or may have a different functionalisation from the lower surface. For example, the upper surface may have one form of active section and the lower surface may have a different form of active section. More than one form of active sec- tion may be used on the upper and/or the lower surface.

Likewise, the substrate may comprise several antimicrobial regions, which may have the same or different active sections. When different active sections are used in different regions the antimicrobial cloth may be used against a broader range of microbes.

In some embodiments, the linking sections have a structure according to Formula I, wherein Formula I is:

Formula I: -0-Si-(CH2)n wherein n is an integer in the range of from 1 to 10, or from 1 to 5, or preferably n is 3.

These linking sections ensure that the active section is positioned appropriately in relation to the surface of the cloth. For example, linking sections having an alkyl chain with a backbone of from 2 to 8 carbon atoms have been found to provide an optimal distance between the respective surface of the antimicrobial cloth and the active section.

Silicon atoms of adjacent linking sections may be bonded via an oxygen atom. Alternatively, the silicon atoms may have suitable additional groups bonded, such as -OH groups, -OCH3 groups or -OCH2CH3 groups. Such sub- stituents are well known to the person skilled in the art.

For example, Formula I represented as -O-Si-(CH2)_n- represents structures in which the Si has any suitable additional substituents. Thus, it could also be represented as -O-Si(O-Y)2(CH2)_n- wherein Y is any suitable compo- nent, such as a methyl group, an ethyl group, another alkyl group or the Si atom of an adjacent linking section.

In some embodiments, the active sections have a structure according to Formula II, wherein Formula II is:

Formula II: -N⁺R¹ R²R³

wherein R¹ is selected from alkyl chains having a backbone of from 4 to 30 carbon atoms;

and further wherein R² and R³ are each independently selected from methyl and ethyl groups. Optionally, R¹ is selected from alkyl chains having a backbone of from 4 to 20 carbon atoms, or from 4 to 10 carbon atoms, or from 10 to 20 carbon atoms.

In some embodiments, the cloth comprises linking sections with a structure according to Formula I and active sections with a structure according to Formula II:

Formula I: -O-Si-(CH₂)3- Formula II: -N⁺(CH₃)2-(CH₂)n-CH3

wherein silicon atoms of adjacent linking sections are bonded via an oxygen atom, and wherein n is an integer in the range of 6 to 10.

Formula I: -O-Si-(CH₂)3-

Formula II: -N⁺(CH₃)2-(CH₂)i7-CH₃

wherein silicon atoms of adjacent linking sections are bonded via an oxygen atom.

The material of the substrate may be chosen freely, provided that it is a microfiber material. A substrate consisting of fibres may also be referred to as a "fabric", and any kind of microfiber fabric is relevant as substrate for the antimicrobial cloth. Any type of fibres may be used for the substrate, such as fibres derived from plant material, e.g. from seeds, leaves, bast, fruits or stalks, or fibres of animal origin, e.g. from hair or silk. Appropriate plant fibres comprise cotton, kapok, hemp and flax. Appropriate animal fibres comprise chitin and chitosan. Synthetic microfibers such as polyester, polyamide or polypropylene may be used. Polyethylene terephthalate and nylon are particularly favourable. The substrate may be made from only one type of fibre, or from multiple types of fibre.

In some embodiments, at least 80wt% of the fibres in the substrate are microfibers, preferably at least 90wt%, more preferably at least 95wt%, more preferably at least 98%. In some embodiments, substantially all of the fibres in the substrate are microfibers. The wt% refers to the total weight of the fibres in the substrate.

The microfiber substrate may comprise polyester in an amount of from 60 - 100 wt%, based on the weight of the fibres of the substrate (i.e. excluding the weight of the antimicrobial functionalisation). Thus, the microfiber may be made entirely from polyester (polyethylene terephthalate), or may be a mixture of polyester (polyethylene terephthalate) with one or more other components.

In some embodiments, the substrate comprises polyester (polyethylene terephthalate) and polyamide (nylon). There may, for example, be 60 - 85wt% polyester and the remaining weight fraction is made up of polyamide, such as nylon. Preferred embodiments include those in which there is 70wt% polyester and 30wt% polyamide and those in which there is 80wt% polyester and 20wt% polyamide.

These materials have been found to provide a particularly favourable balance between cost, weight (and thus ease of transport), ability to function- alise with antimicrobial properties, ability remove bacteria from a surface and hand-feel of the material. It is also possible to combine more than one type of fibre, and combinations may be of natural fibres, synthetic fibres, or natural fibres may be combined with synthetic fibres. In a preferred embodiment, the substrate is a fabric, woven or non-woven, with fibres of blended polyester with any suitable sec- ondary material. The substrate may be a fabric, and the fabric may be woven or non-woven. In other embodiments, the substrate is a fabric, which is crocheted, knitted or warp-knitted.

The linking sections comprise a silicon atom between the linking alkyl chain and the substrate, the silicon atom covalently bonding the linking alkyl chain of the linking section to the substrate. It has been found that silicon is particularly effective at keeping the antimicrobial functionalisation bonded to the substrate surface, whilst being safe for contact with the skin. In general, a silicon atom will form a covalent bond to the surface of the substrate via an oxygen atom in the surface of the substrate, and it is preferred that the sub- strate comprises, or is made of, a material, e.g. a polymer material, such as fibres of a polymer material, having available atoms, such as oxygen or nitrogen atoms. Available oxygen atoms may, for example be present for example in the form of hydroxyl groups.

Preferably, silicon atoms of adjacent linking sections are bonded, e.g. covalently bonded, via an oxygen atom. In this way, a matrix arrangement is formed in which linking sections are not only connected to the surface of the substrate, but also one another. This increases the stability of the functionalisation. Even if a link between a silicon atom and a surface of the substrate is broken, the corresponding active section will still be held in place as the silicon atom is bonded to the neighbouring linking sections. This improves the antimicrobial cloth's ability to withstand repeated washes without losing antimicrobial properties. Typically, such an antimicrobial cloth can withstand at least 100 washes, but the lifetime of the cloth is generally determined by the durability of the substrate, more than the durability of the antimicrobial treatment.

In some embodiments, the substrate comprises or consists of filaments below 0.8 denier, preferably below 0.5 denier, preferably below 0.3 denier, more preferably the filaments are 0.26 denier. This size may apply to at least 80% of the fibres, preferably at least 90%, more preferably at least 95%, more preferably at least 98%. In some embodiments, substantially all of the fibres in the substrate are of this size range.

It has surprisingly been found that substrates made from thin filaments i.e. filaments as described above, are particularly effective at capturing bacteria from a surface and ensuring that the bacteria is transferred from the surface onto the cloth.

The filaments of the microfiber substrate may be present in the form of a yarn, wherein each yarn comprises from 2 to 10 filaments, preferably 8 filaments. The filaments may be spun to form the yarn.

The substrate may comprise strands, wherein each strand comprises a plurality of yarns. The strands may comprise at least 36 yarns, preferably around 72 yarns. The strands may be at least 100 denier, preferably 150 denier or more. The strands may be less than 200 denier. The number of filaments in a yarn and the number of yarns in a strand may be selected to give the desired strand characteristic, for example to give a strand of at least 100 denier or around 150 denier.

Such substrates have been found to be particularly effective at capturing bacteria from a surface and ensuring that the bacteria is transferred from the surface onto the cloth.

In some embodiments, the antimicrobial region has an area in the range of from 10% to 100% of the area of the upper surface and/or in the range of from 10% to 100% of the area of the lower surface. It will be understood that in some embodiments, the surface coverage used will depend, inter alia, on the size of the antimicrobial cloth and/or its intended purpose. In a preferred em- bodiment, the antimicrobial cloth is fully functionalised so that the antimicrobial region has an area of 100% of the area of the upper surface and an area of 100% of the area of the lower surface. The larger the relative amount of the antimicrobial region in the surface area of the upper and the lower surfaces, the more efficient the use of the water applied to the antimicrobial cloth. If the substrate has unfunctionalised regions these will also absorb water, which then will not be available to the functionalised regions, and thus the higher the percentage of the surface of the substrate, which has the functionalisation the less water is needed. For example, a typical fabric used for a cloth absorbs water at about 0.1 ml/cm², and in use water may be applied to the antimicrobial cloth, or to the antimicrobial region, in the range of 0.05 ml/cm² to 1 .0 ml/cm² for sanitation of a surface, e.g. the hands of a human being. When water is scarce it is therefore particularly advantageous to select a small antimicrobial cloth, and in particular an antimicrobial cloth where the upper surface and the lower surface are fully functionalised so that the antimicrobial region corresponds to the total available surface of the antimicrobial cloth, since this embodiment ensures more efficient use the available water.

Any suitable surface area of the substrate may be used. For example, the surface area of the antimicrobial region may be in the range of 1 cm² to 10 cm². Antimicrobial cloths having this area of functionalisation are useful for cleaning small surfaces. Cloths such as this can be mounted on a handle or other similar object to facilitate their use.

Alternatively, the surface area of the antimicrobial functionalisation may be in the range of 250 cm² to 2500 cm², 500 cm² to 2000 cm², 750 cm² to 1750 cm² or 1000 cm² to 1500 cm². Antimicrobial cloths with antimicrobial func- tionalisations of these surface areas are particularly well suited to use by hand. In other embodiments the surface area of the antimicrobial functionalisation may also be larger than 2500 cm². For example, the antimicrobial cloth may have a size of up to 10,000 cm², and the antimicrobial cloth may be fully functionalised over the entire surface or a section of the surface.

It will be understood that where the antimicrobial functionalisation is applied to the upper and lower surface, the surface area of the functionalisation on each surface may be in one of the specified ranges or the total surface area of the antimicrobial functionalisation may be in one of these ranges.

The antimicrobial cloth and the antimicrobial region may be of any shape. For example, the antimicrobial functionalisation may be square or rectangular with dimensions in the range of 20 cm to 50 cm x 20 cm to 50 cm. The antimicrobial cloth, and/or the antimicrobial functionalisation, may also be round, e.g. with a diameter in the range of 5 cm to 50 cm. It will be understood that these shapes do not preclude deviations to the shape of the boundary.

The antimicrobial cloth may have a thickness in the range of from 0.1 mm to 2 mm. Cloths of this thickness are particularly easy to transport and store and dry quickly after washing. Moreover, the thinner the cloth the less water required for using the antimicrobial cloth. In other embodiments, e.g. when the substrate is a fabric, which is crocheted, knitted or warp-knitted the thickness may be higher, e.g. 2 mm to 4 mm, e.g. 3 mm.

In some embodiments, the cloth does not comprise an absorbent layer.

It will be understood that this does not preclude the cloth/substrate per se having the capability to absorb some liquid. In particular, the antimicrobial cloth may not provide an antimicrobial effect if it is dry. When an absorbent layer is present in the antimicrobial cloth, the absorbent layer can absorb the water to an extent where it prevents or hinders the antimicrobial effect of the antimicrobial functionalisation, so that efficient sanitisation cannot be ensured. However, in these embodiments the cloth is not bonded to, or otherwise connected with, a layer of absorbent material. In this way, the absorbent cloth does not retain liquid unnecessarily and is therefore easy to wash and quick to dry. Further- more, if the antimicrobial cloth contained an adsorbent layer, e.g. an absorbent layer not containing active sections, the absorbent layer may retain microbes from any liquid in contact with the antimicrobial cloth and lower, or even prevent, the antimicrobial effect. Also, any absorbent layer present would remove moisture from the substrate and could therefore reduce the effectiveness of the antimicrobial functionalisation.

According to a second aspect of the present invention, there is provided a method of reducing the number of living microbes on a microbe-containing surface, the method comprising the steps of:

- providing an antimicrobial cloth according to a first aspect of the pre- sent invention;

- applying water to the antimicrobial cloth; and

-wiping the surface with the antimicrobial cloth.

The amount of water will generally be in the range of 0.05 ml/cm² to 1 .0 ml/cm², e.g. in the range of 0.06 ml/cm² to 0.5 ml/cm², or 0.07 ml/cm² to 0.2 ml/cm², or 0.08 ml/cm² to 0.1 ml/cm². The method of the present invention advantageously allows sanitisation to take place faster than traditional washing with soap and water. In particular, the antimicrobial cloth allows sanitisation using less water than required when washing with soap and water. For example, the presently identified international standard suggests that hand washing should be performed for 40 to 60 seconds (WHO, Hand Hygiene: Why, How & When?, August 2009) in order to ensure that the hands are clean. In contrast, the antimicrobial cloth of the present invention allows that the >99% of bacteria attracted by the functionalisation of the substrate are killed in a few seconds. Thereby, the antimicrobial cloth allows sanitisation of a pair of hands in about 30 seconds. Thus, the method of the invention provides both faster sanitisation and also requires less water.

The surface may be any suitable surface. Examples of suitable surfaces include hands or another surface of a human being or an animal. The method is effective at reducing the number of living microbes, even when little water is used. The surface may also be that of another object, e.g. a table, a furniture surface, a tray, cutlery, kitchen utensils, a kitchen sink, etc.

It will be understood that the amount of water is an average value.

In some regions the amount may be higher and in other parts the amount maybe lower, but the average amount of water applied over the surface will be within the specified range.

It will be understood that the term "backbone" is used to describe the longest carbon chain. For example, an unsubstituted octyl chain has a backbone of 8 carbons. If the octyl group is substituted at the C1 position with an ethyl group, the backbone would then be 10 carbons long. If the octyl group is substituted at the C5 position with an ethyl group, the backbone would be 8 carbons long. This is consistent with conventional practices in the field.

Unless otherwise indicated, or not applicable, all % are wt percentages.

It will be understood that references to the upper surface and lower surface are references to the two surfaces of the cloth. They are not dependent on the orientation of the cloth and so in any orientation the cloth can still be considered to have an upper surface and a lower surface.

Denier is a well-recognised unit in the field. It represents the unit of measure for the mass of a given length of fibre.

A microfiber substrate is a substrate in which some, possibly all of the filaments are of 1 denier or less. Brief Description of Drawings

The present invention will now be described, by way of example, by reference to the accompanying drawings in which:

Figure 1 shows a schematic representation of an antimicrobial cloth according to the present invention;

Figure 2 shows a schematic representation of a portion of the surface of an antimicrobial cloth of the present invention;

Figure 3 shows an expanded schematic representation of a portion of the surface shown in Figure 2;

Figure 4 shows a chemical symbol representation of the schematic of Figure 3; and

Figure 5 is a schematic representation of a different antimicrobial cloth according to the present invention.

Description of Embodiments

The antimicrobial cloth 1 of Figure 1 has an antimicrobial functionalisa- tion 4 bonded to upper surface 6. The lower surface is not shown, but in this embodiment, it also has an antimicrobial functionalisation. The antimicrobial cloth 1 shown is a generally rectangular shape and the majority of the top surface 6 is covered with the antimicrobial functionalisation 4. The substrate 2 is made from a fabric comprising a blend of 80wt% polyester and 20wt% nylon.

A portion of top surface 6 of antimicrobial cloth 1 is shown in Figure 2. The linking sections 12 and corresponding active sections 10 are shown sche- matically for simplicity. In the region shown all of the active sections are the same. However, it will be understood that this only applies for some embodiments. In other embodiments, the active sections may differ from one another. For simplicity, connections between the linking sections are not shown.

Figure 3 shows an expanded version of portion of top surface 6 shown in box A of Figure 2. Here, active sections 10 are shown separately from the linking sections 12. The linking sections are joined together by bonds 14. Co- valent bonds 16 connect the linking section 12 with active sections 10. Linking sections 12 are bonded to the top surface 6 via bonds 18. Figure 4 is similar to Figure 3, except that a specific example of the linking sections 12 and active sections 10 are shown in terms of their chemical symbols.

In the embodiment shown, the nitrogen has an 8 carbon chain in the active section. However, alternative embodiments are envisaged, such as embodiments in which the -(CH2)7-CH3 group is instead a -(CH2)i 7-CH3 group.

Likewise, each Si group is shown with two OCH3 groups. These could alternatively be OH, or O-Et groups, or the adjacent linking sections could be joined via Si-O-Si bonds, as represented schematically in Fig. 3.

In Figure 5, the same reference numbers are used as in Figure 1 for elements having the same function even though they are embodied differently.

The antimicrobial cloth 1 of Figure 5 has an antimicrobial functionalisa- tion 4 bonded to top surface 6. The bottom surface is not shown, but it also has an antimicrobial functionalisation. The antimicrobial cloth shown is a generally rectangular shape and the majority of the top surface 6 is covered with the antimicrobial functionalisation 4. The antimicrobial functionalisation has two different parts. First part 42 uses a first type of active section and second part 44 uses a second type of active section. The second part 44 is shown within the first part, although any suitable arrangement may be used. For example, the first part could be inside the second part, or the two parts could be side-by-side. It is, however, preferred that both surfaces of the substrate 2 are fully function- alised, i.e. 100% of the respective surfaces are functionalised.

Optionally, the cloth 1 may have a scrubbing pad (not shown) in one or more corners of the cloth. The scrubbing pad(s) may be on the top surface, bottom surface or both and will be made from a different material from the rest of the cloth. The scrubbing pad may for example be a nail scrubbing pad.

Manufacture

A silanisation process can be used to form the antimicrobial functionalisation and connect it to the antimicrobial cloth. Silanisation is a routine procedure for the skilled person and would be well understood.

Typically, aminosilanes such as (3-aminopropyl)triethoxysilane or (3- aminopropyl)-trimethoxysilane, or the like, are used as starting material. The alkoxy groups are reactive and can therefore be displaced, and the molecules polymerised. This property is utilised to connect the aminosilanes to one another and to available oxygen atoms on the surface of the antimicrobial cloth, for example hydroxyl groups of a polyester.

For example, (3-aminopropyl)triethoxysilane can be reacted with a polyester substrate to provide a substrate having 3-aminopropyl groups. The substrate with 3-aminopropyl groups can then be reacted with an appropriate reactive component, e.g. 1 -chlorooctane, to provide a substrate shown in Formula III.

The result is a network in which linking sections are connected to one another and to the antimicrobial cloth. The amino group can be functionalised to give R groups as desired. It will be understood that the functionalisation of the amino group can occur before or after the connection with the antimicrobial cloth has been established.

Quaternary ammonium organosilane compounds are also commercially available, for example product AEM 5772 from Aegis®. Such compounds are known to the skilled person. They can be bonded to the substrate in any suitable way, such as by the reactions that follow. These are presented by way of illustration and are not intended to be limiting.

For example, quaternary ammonium organosilane compounds can be dissolved in an appropriate solvent (such as water) and then be sprayed or brushed on the cloth followed by drying at e.g. 80 °C for 30 minutes for complete condensation of Silanol groups and to remove water from the hydrolysis.

In another example, quaternary ammonium organosilane compounds are dissolved in an appropriate solvent at the desired concentration. The cloth then is dipped into the dilution and afterwards dried at e.g. 120 °C for 5 minutes.

In another example, quaternary ammonium organosilane compunds are connected to the cloth via an exhaustion process. The compound is dissolved according to a desired liquor ratio and the cloth is immersed into the dilution for 10 - 40 minutes followed by drying at 40 °C for 20 - 30 minutes.

Substrates may be formed in any suitable way and means for forming microfiber substrates are known to the person in the art.

Claims

P A T E N T C L A I M S

1 . An antimicrobial cloth comprising a microfiber substrate having an upper and a lower surface, the substrate comprising an antimicrobial function- alisation in an antimicrobial region, the antimicrobial region being on the upper surface and/or the lower surface, the antimicrobial functionalisation comprising linking sections joined to active sections and to the substrate in the antimicrobial region,

Formula I: -0-Si-(CH₂)_n- wherein n is an integer in the range from 1 to 15

the active sections having a structure according to Formula II, wherein

Formula II is:

Formula II: -N⁺R¹ R²R³

and wherein R² and R³ are each independently selected from alkyl chains having a backbone of from 1 to 30 carbon atoms, wherein one or more hydrogen atoms may be substituted with a halogen atom or a straight or branched alkyl group having from 1 to 10 carbon atoms, wherein one or more hydrogens on the straight or branched alkyl group having from 1 to 10 carbon atoms may be substituted with a halogen atom;

and wherein the microfiber substrate comprises filaments of 1 denier or less.

2. The antimicrobial cloth according to Claim 1 , wherein the linking sections have a structure according to Formula I, wherein Formula I is: Formula I: -0-Si-(CH₂)_n- wherein n is an integer in the range of from 1 to 10, or from 1 to 5, or preferably n is 3.

3. The antimicrobial cloth according to any of Claims 1 or 2, wherein the active sections have a structure according to Formula II, wherein Formula

II is:

Formula II: -N⁺R¹ R²R³

and further wherein R² and R³ are each independently selected from methyl and ethyl groups.

4. The antimicrobial cloth according to Claim 3, wherein R¹ is selected from alkyl chains having a backbone of from 4 to 20 carbon atoms, or from 4 to 10 carbon atoms, or from 10 to 20 carbon atoms.

5. The antimicrobial cloth according to any preceding claim, wherein silicon atoms of adjacent linking sections are bonded via an oxygen atom.

6. The antimicrobial cloth according to any preceding claim, comprising linking sections with a structure according to Formula I and active sections with a structure according to Formula II:

Formula I: -0-Si-(CH₂)₃-

Formula II: -N⁺(CH₃)2-(CH₂)n-CH3

7. The antimicrobial cloth according to any of Claims 1 to 5, comprising linking sections with a structure according to Formula I and active sections with a structure according to Formula II:

Formula I: -0-Si-(CH₂)3- Formula II: -N⁺(CH₃)2-(CH₂)i 7-CH₃

8. The antimicrobial cloth according to any preceding claim, wherein the antimicrobial region has an area in the range of from 10% to 100% of the area of the upper surface and/or in the range of from 10% to 100% of the area of the lower surface.

9. The antimicrobial cloth according to any preceding claim, wherein the microfiber substrate comprises polyester in an amount from 60 to 100 wt%.

10. The antimicrobial cloth according to claim 9, wherein the microfiber substrate further comprises a polyamide in an amount from 0 to 40 wt%.

1 1 . The antimicrobial cloth according to any preceding claim, wherein the substrate comprises or consists of filaments below 0.8 denier, preferably below 0.5 denier, preferably below 0.3 denier, more preferably the filaments are 0.26 denier.

12. The antimicrobial cloth according to any preceding claim, wherein the filaments of the microfiber substrate are present in the form of a yarn, wherein each yarn comprises from 2 to 10 filaments, preferably 8 filaments.

13. The antimicrobial cloth according to Claim 12, wherein the substrate comprises strands, wherein each strand comprises a plurality of yarns.

14. The antimicrobial cloth of Claim 13, wherein the strands comprise at least 36 yarns, preferably 72 yarns and the strands are at least 100 denier, preferably 150 denier or more.

15. The antimicrobial cloth according to any preceding claim, wherein the substrate has a thickness in the range of from 0.1 mm to 2 mm.

16. The antimicrobial cloth according to any preceding claim, which does not comprise an absorbent layer.

17. The antimicrobial cloth according to any preceding claim, wherein the antimicrobial functionalisation constitutes from 0.5 to 10 wt% of the cloth, preferably 1 .5 to 9 wt% of the cloth.

18. A method of reducing the number of living microbes on a microbe- containing surface, the method comprising the steps of:

- providing an antimicrobial cloth according to any one of Claims 1 to

17;

- applying water to the antimicrobial cloth or the microbe-containing surface; and

-wiping the surface with the antimicrobial cloth.