WO2015075462A1

WO2015075462A1 - Composition

Info

Publication number: WO2015075462A1
Application number: PCT/GB2014/053443
Authority: WO
Inventors: Stephen Brian Falder; Jonathan Stewart FALDER
Original assignee: Preservation Paints Limited
Priority date: 2013-11-20
Filing date: 2014-11-20
Publication date: 2015-05-28
Also published as: GB201420672D0; GB201320504D0; GB2522319A

Abstract

The present invention provides a liquid coating composition comprising: (a) carbon nanotubes; (b) a fluorinated polyurethane or a urethane polymer modified with a perfluoroalkylsulfonamide; (c) a resin binder; and (d) a solvent; wherein an ingredient may be both component (b) and component (c) or component (b) and component (c) may independently be separate ingredients.

Description

COMPOSITION

The present invention is related to hydrophobic coating compositions. Hydrophobic coatings have been available for many years and are often based on silicones and/or siloxanes. Their advantages include making treated surfaces water repellent thus providing protection from water damage or spoilage. Other hydrophobic coatings may include fluorocarbons or fluorocarbon derivatives, which have the additional benefit of being lipophobic as well as hydrophobic.

These known coatings, however, have disadvantages. For example, they do not allow transmission of vapours in either direction, and they do not protect the substrate effectively from UV damage/bleaching/deterioration. Further weaknesses include the fact that these coatings are electrically inert, this gives them the capacity to hold a static charge and thus attract dust, and also they tend to be relatively weak film forming materials.

The listing or discussion of an apparently prior-published document in this specification should not necessarily be taken as an acknowledgement that the document is part of the state of the art or is common general knowledge.

It would be advantageous to develop new hydrophobic coating compositions that overcome one or more of these problems. The present inventors have surprisingly found that the incorporation of carbon nanotubes into a hydrophobic liquid coating composition significantly improves the performance of hydrophobic coating compositions. One or more of the following advantages can be achieved. In comparison to a hydrophobic coating that does not comprise carbon nanotubes, coatings that comprise carbon nanotubes have been found to:

• be more durable and thus may have increased service life; and/or

• have improved vapour permeability; and/or

• reduce deterioration of the substrate as a result of exposure to ultraviolet light; and/or

• have improved mechanical properties, particularly in terms of strength; and/or • have improved electrical properties, thus reducing dust attraction and similar dirt retention.

A particular advantage of using carbon nanotubes in hydrophobic coating compositions is that they are not visible to the naked eye and therefore do not visibly alter the appearance of the composition or the coating.

Without wishing to be bound by theory, it is thought that the presence of carbon nanotubes in the compositions of the invention and in the resulting coatings allows the transmission of small molecules through the composition/coating and that this can facilitate vapour permeability. For example, this can reduce water retention and reduce freeze and/or thaw damage.

Without wishing to be bound by theory, it is thought that the carbon nanotubes can absorb ultraviolet light and thus help prevent or reduce ultraviolet damage to a substrate to which a composition of the invention is applied to form a coating and/or improve adhesion of the coating to the substrate surface.

Without wishing to be bound by theory, it is thought that the inclusion of carbon nanotubes in a composition of the invention can enhance the mechanical strength of a coating obtained when the composition is applied to a substrate.

Without wishing to be bound by theory, it is thought that the inclusion of carbon nanotubes in a composition of the invention can increase the electrical conductivity of the composition and the resulting coating. This can reduce or prevent static build up, which can be a safety hazard. This can also facilitate corrosion management. This can also reduce dust attraction and similar dirt retention.

The present invention provides a liquid composition comprising:

(a) carbon nanotubes; (b) a fluorinated polyurethane and/or a urethane polymer modified with perfluoroalkylsulfonamide; (c) a resin binder; and (d) a solvent, wherein an ingredient may be both component (b) and component (c) or component (b) and component (c) may be independently separate ingredients. Such compositions are hereinafter referred to as compositions of the invention. As an example, the compositions of the invention may contain a single ingredient that satisfies the definition of both component (b) and (c) or two or more ingredients that satisfy the definition of both component (b) and component (c). In an aspect of the invention the liquid composition may optionally further comprise (e) one or more silicones and/or one or more siloxanes.

For example, a liquid composition of the invention may comprise (a) carbon nanotubes; (b) a fluorinated polyurethane and a urethane polymer modified with perfluoroalkylsulfonamide; (c) a resin binder; (d) a solvent; and optionally (e) one or more silicones and/or one or more siloxanes, wherein an ingredient may be both component (b) and component (c) or component (b) and component (c) may be independently separate ingredients; or may comprise (a) carbon nanotubes; (b) a fluorinated polyurethane; (c) a resin binder; (d) a solvent; and optionally (e) one or more silicones and/or one or more siloxanes, wherein an ingredient may be both component (b) and component (c) or component (b) and component (c) may be independently separate ingredients; or may comprise (a) carbon nanotubes; (b) a urethane polymer modified with perfluoroalkylsulfonamide; (c) a resin binder; (d) a solvent, and optionally (e) one or more silicones and/or one or more siloxanes, wherein an ingredient may be both component (b) and component (c) or component (b) and component (c) may be independently separate ingredients.

The liquid compositions of the invention are typically used as coating compositions. In other words, they are coating compositions or hydrophobic coating compositions. This means that in use the compositions of the invention are applied to a substrate to be treated, the composition then dries or coalesces on the substrate to provide a coating or layer on the substrate. That coating or layer is typically hydrophobic.

Alternatively, the compositions of the invention can be termed as "film-forming" compositions. By this we mean that when a composition of the invention is applied to a substrate, the composition dries or coalesces to form a film on the substrate.

For the avoidance of doubt, in this specification when we use the term "comprising" or "comprises" we mean that the composition or formulation or component being described must contain the listed ingredient(s) but may optionally contain additional ingredients. When we use the term "consisting essentially of or "consists essentially of" we mean that the composition or formulation or component being described must contain the listed ingredient(s) and may also contain small (for example up to 5% by weight, or up to 1 % or 0.1 % by weight) of other ingredients provided that any additional ingredients do not affect the essential properties of the composition, formulation or component. When we use the term "consisting of we mean that the composition or formulation or component being described contains the listed ingredient(s) only, however, this will not prevent that composition formulation or component containing solvents or other additional ingredients that are present in a commercially obtained component or ingredient.

By the term "hydrophobic" we mean that the composition or ingredient (e.g. a coating surface) provides a wettability of a surface, that has a water contact angle of 90° or greater, or 120° or greater or 130° or greater when calculated using the Young Equation. In one aspect, we mean that the liquid coating composition has a water contact angle of 90° or greater, or 120° or greater or 130° or greater when calculated using the Young Equation.

By the term "fluorinated polyurethane" we mean a polyurethane in which in substantially every dialcohol monomer within the polyurethane and/or substantially every diisocyanate monomer within the polyurethane, at least one hydrogen atom has been replaced with a fluorine atom. For example, this term includes a polyurethane in which in at least about 50%, such as at least about 60% or about 70% or about 80% or about 90% or about 100% of the dialcohol monomer within the polyurethane, at least one hydrogen atom has been replaced with a fluorine atom and/or in which in at least about 50% such as at least about 60% or about 70% or about 80% or about 90% or about 100% of the diisocyanate monomer within the polyurethane, at least one hydrogen atom has been replaced with a fluorine atom.

For example, fluorinated polyurethanes suitable for use in the present invention include those in which at least about 10% of the hydrogen atoms have been replaced with a fluorine atom, such as at least about 20% or about 30% or about 40% or about 50% or about 60% or about 70% or about 80% or about 90% or about 100% of the hydrogen atoms in the dialcohol monomer(s) and/or at least about 20% or about 30% or about 40% or about 50% or about 60% or about 70% or about 80% or about 90% or about 100% of the hydrogen atoms in the diisocyanate monomer(s) have been replaced with fluorine atoms providing a fluorinated polyurethane wherein at least about 10% of the hydrogen atoms have been replaced with a fluorine atom, such as at least about 20% or about 30% or about 40% or about 50% or about 60% or about 70% or about 80% or about 90% or about 100% of the hydrogen atoms have been replaced with fluorine atoms.

In an aspect of the invention from about 10% to about 100% of the hydrogen atoms in the dialcohol monomer have been replaced with a fluorine atom, such as from about 20% to about 80%, or from about 30% to about 70% or from about 40% to about 60% and/or from about 10% to about 100% of the hydrogen atoms in the diisocyanate monomer have been replaced with a fluorine atom, such as from about 20% to about 80%, or from about 30% to about 70% or from about 40% to about 60%.

By the term "urethane polymer modified with a perfluoroalkylsulfonamide" we mean a urethane polymer that comprises at least one perfluoroalkylsulfonamide-based substituent, wherein, for example, the perfluorosulfonamide-based substituent results from the reaction of at least about 20% of the nitrogen atoms in the urethane monomers or at least about 20% of the nitrogen atoms in the pre-formed urethane polymer with a compound of the following general formula:

wherein n is from 1 to 20, such as from 2 to 10, 2 to 4, or 6.

For example, the perfluorosulfonamide-based substituent may result from the reaction of at least about 40%, such as at least about 50% or about 60% or about 70% or about 80% or about 90% or about 100% of the nitrogen atoms in the urethane monomers or at least about 40%, such as at least 50% or about 60% or about 70% or about 80% or about 90% or about 100% of the nitrogen atoms in the pre-formed urethane polymer with the perfluorinated sulfonic acid compound above.

In an aspect of the invention, the perfluorosulfonamide-based substituent may result from the reaction of at least about 90% to about 100% of the nitrogen atoms in the urethane monomers or at least about 90% to about 100% of the nitrogen atoms in the pre-formed urethane polymer with the perfluorinated sulfonic acid compound above.

As described above, the liquid coating composition of the invention may optionally include (e) one or more silicones and/or one or more siloxanes. By the term "silicones", we mean silicones such as those having the structure:

Wherein A and B are each independently hydrocarbon groups, for example hydrocarbon groups containing from 1 to 12 carbon atoms or from 1 to 6 carbon atoms or from 1 to 4 carbon atoms and m and n are each independently an integer, of from 1 to 24, more preferably from 1 to 12 and most preferably from 1 to 8, for example n may be 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, especially 1 , 2, 3 or 4. Suitable groups for A and B include alkyl groups such as methyl or ethyl groups, alkenyl groups and aryl groups such as phenyl.

Alternatively or additionally, cyclic silicones may be used. Suitable cyclic silicones include those containing 3 to 10 membered rings. Silicones that are suitable for use in the present invention are liquid at normal operating temperatures. Suitable silicones include those that are liquid at from about -10 °C to about 40 °C, such as from about 0 °C to about 30 °C. In particular, silicones that are liquid at room temperature (from about 15 °C to about 25 °C, such as about 20 °C) are suitable for use in the present invention.

Silicones that are suitable for use in the present invention include those which are known for use in the fields of surface treatment and surface coatings.

By the term "siloxanes", we mean siloxanes such as those having the formulae (H₃C)[SiO(CH3)2]nSi(CH₃)3, or (H₃C)[SiO(CH3)H]nSi(CH₃)3, and mixtures thereof, where n is an integer, of from 1 to 24, more preferably from 1 to 12 and most preferably from 1 to 8, for example n may be 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, especially 1 , 2, 3 or 4. These materials are often referred to as (poly)dimethylsiloxanes (CAS # 9016-00-6) and (poly)methylhydrosiloxanes respectively. These materials are typically liquid at ambient temperature and pressure (e.g. about 20°C at atmospheric pressure).

Other siloxanes suitable for use in the present invention include cyclic siloxanes having the structure (Si(CH₃)20)_n, wherein n is from 3 to 10, such as from 3 to 6, for example n is 3, 4, 5 or 6. The silicones used in the present invention typically have a viscosity of up to about 350 cSt at room temperature (e.g. about 20°C and at atmospheric pressure). Component (b) is typically present in the compositions of the invention in an amount of from about 0.1 to 50% by weight, for example from 1 to 35% by weight, more preferably from 1.5 to 30% by weight, more preferably 2 to 10% by weight, relative to the total weight of the liquid composition. An example of a commercially available fluorinated polyurethane suitable for use in the present invention is sold under the trade name SRC-220 by 3M (USA).

SRC-220 is sold in an aqueous solution. The composition of SRC-220 is:

Water (CAS 7732-18-5) 75 - 85 wt% Urethane polymer modified with perfluoroalkylsulfonamide Trade Secret 10 - 20 wt% 2-Methoxymethylethoxypropanol (CAS 34590-94-8) 3 - 7 wt%

Therefore, if SRC-220 contains 20 wt% urethane polymer modified with perfluoroalkylsulfonamide, and a composition of the invention contains 19% of SRC-220, the composition contains 3.8% urethane polymer modified with perfluoroalkylsulfonamide.

Some ingredients that may be used as Component (b) may also have resin binder properties. Therefore, a single ingredient or two or more ingredients may be both component (b) and component (c). Alternatively, component (b) and component (c) may be independently separate ingredients.

The silicones and/or siloxanes, optional component (e), do not have resin binder properties. The ingredient that has resin binder properties aids formation of a coating or film. As stated above, this may be component (b) or alternatively a separate resin binder ingredient may be used. It is also envisaged that even if component (b) has resin binder properties an additional resin binder component may be used in some compositions of the invention.

Suitable resin binders that are not within the definition of component (b) include, but are not limited to, synthetic or natural resins such as alkyds, acrylics, vinyl-acrylics, vinyl acetate/ethylene (VAE), polyurethanes, polyesters, melamine resins, epoxy, or oils. Water borne and/or solvent borne resins may be used depending on the hydrophobic agent being used and composition of the formula. The amount of resin binder (component (c)) used in a composition of the invention will depend on the nature of the resin binder, the nature of component (b) and the nature of other ingredients in the composition. The resin binder may for example be present in an amount of from about 0.5 to about 15% by weight of the composition, such as from about 1 .0 to about 10% by weight of the composition or from about 2.0 to about 8.0% by weight, relative to the total weight of the liquid composition.

When the same ingredient(s) are present in a composition of the invention as both component (b) and component (c) the total amount of that ingredient/those ingredients may be for example from about 0.1 to 65% by weight, for example from 1 to 45% by weight, more preferably from 1 .5 to 40% by weight, more preferably 2 to 20% by weight, relative to the total weight of the liquid composition.

In an aspect of the invention component (b) and component (c) may be provided by using a mixture of a fluorinated polyurethane and a urethane polymer modified with perfluoroalkylsulfonamide.

Suitable solvents for use in the present invention include polar solvents. Suitable polar solvents include, but are not limited to, water, alcohols, esters, hydroxy and glycol esters, polyols and ketones, and mixtures thereof.

In some aspects of the invention the composition can be non-aqueous. However, it is preferable that the compositions of the invention contain water, optionally with another solvent. Suitable alcohols for use in the present invention include, but are not limited to, straight or branched chain Ci to C5 alcohols, such as methanol, ethanol, n-propanol, iso- propanol, mixtures of propanol isomers, n-butanol, sec-butanol, tert-butanol, iso-butanol, mixtures of butanol isomers 2-methyl-1 -butanol, n-pentanol, mixtures of pentanol isomers and amyl alcohol (mixture of isomers), and mixtures thereof.

Suitable esters for use in the present invention include, but are not limited to, methyl acetate, ethyl acetate, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec-butyl acetate, amyl acetate (mixture of isomers), methylamyl acetate, 2- ethylhexyl acetate and iso-butyl isobutyrate, and mixtures thereof.

Suitable hydroxy and glycol esters for use in the present invention include, but are not limited to, methyl glycol acetate, ethyl glycol acetate, butyl glycol acetate, ethyl diglycol acetate, butyl diglycol acetate, ethyl lactate, n-butyl lactate, 3-methoxy-n-butyl acetate, ethylene glycol diacetate, polysolvan O, 2-methylpropanoic acid-2,2,4-trimethyl-3- hydroxypentyl ester, methyl glycol, ethyl glycol, iso-propyl glycol, 3-methoxybutanol, butyl glycol, iso-butyl glycol, methyl diglycol, ethyl diglycol, butyl diglycol, iso-butyl diglycol, diethylene glycol, dipropylene glycol, ethylene glycol monohexyl ether and diethylene glycol monohexyl ether, 2-methoxymethylethoxypropanol and mixtures thereof.

Suitable polyols for use in the present invention include, but are not limited to, ethylene glycol, propylene glycol, 1 ,3-butylene glycol, 1 ,4-butylene glycol, hexylene glycol, diethylene glycol, triethylene glycol and dipropylene glycol, and mixtures thereof.

Suitable ketones for use in the present invention include, but are not limited to iso-butyl heptyl ketone, cyclohexanone, methyl cyclohexanone, methyl iso-butenyl ketone, pent- oxone, acetyl acetone, diacetone alcohol, iso-phorone, methyl butyl ketone, ethyl propyl ketone, methyl iso-butyl ketone, methyl amyl ketone, methyl iso-amyl ketone, ethyl butyl ketone, ethyl amyl ketone, methyl hexyl ketone, diisopropyl ketone, diisobutyl ketone, acetone, methyl ethyl ketone, methyl propyl ketone and diethyl ketone, and mixtures thereof.

In one aspect, the compositions of the invention contain at least one coalescent solvent, such as a hydroxyl or glycol ester or a polyol.

Suitable hydroxy and glycol esters for use in the present invention include, but are not limited to, methyl glycol acetate, ethyl glycol acetate, butyl glycol acetate, ethyl diglycol acetate, butyl diglycol acetate, ethyl lactate, n-butyl lactate, 3-methoxy-n-butyl acetate, ethylene glycol diacetate, polysolvan O, 2-methylpropanoic acid-2,2,4-trimethyl-3- hydroxypentyl ester, methyl glycol, ethyl glycol, iso-propyl glycol, 3-methoxybutanol, butyl glycol, iso-butyl glycol, methyl diglycol, ethyl diglycol, butyl diglycol, iso-butyl diglycol, diethylene glycol, dipropylene glycol, ethylene glycol monohexyl ether and diethylene glycol monohexyl ether, 2-methoxymethylethoxypropanol and mixtures thereof. Suitable polyols for use in the present invention include, but are not limited to, ethylene glycol, propylene glycol, 1 ,3-butylene glycol, 1 ,4-butylene glycol, hexylene glycol, diethylene glycol, triethylene glycol and dipropylene glycol, and mixtures thereof. An example of a suitable combination of solvents is a solvent and a coalescent solvent.

An example of a suitable combination of solvents is water and a hydroxy or glycol ester, such as water and butyl glycol or water and 2-methoxymethylethoxypropanol. Up to about 99% by weight of a composition of the invention may be solvent. For example, from about 10% to about 99% by weight of the composition may be solvent, such as from about 30 to about 95% by weight or about 40 to about 90% by weight or about 40 to about 85% by weight, such as about 80% by weight, relative to the total weight of the liquid composition.

If the composition contains a coalescent solvent, the amount of coalescent solvent can be from about 5 to about 85% by weight of the composition. This range is large because the coalescent solvent may be the primary (main) solvent or a secondary solvent. Additionally, different compositions may require different levels of coalescence.

If the solvent component is composed of more than one solvent, the relative amounts of each solvent can vary within wide limits. For example, if the solvent component contains two solvents the ratio of the two solvents may be about 1 :1 or may vary from about 1 :10 to about 10: 1. For example, suitable ratios may be from about 5: 1 to about 1 :5 or from about 3:1 to about 1 :3 or about 2:1 to about 1 :2. For example, if the solvent is a combination of water and butyl glycol the ratio of water to butyl glycol may be about 1 :3.

After application to a surface, coalescence of the liquid composition of the invention takes place to form a film. This film forms at ambient temperature (e.g. from about 0 to about 40 °C), such as from about 10 to about 30 °C or from about 15 to about 25 °C.

In one aspect of the invention, it is advantageous for the compositions to have a low viscosity, for example a viscosity for from about 0.1 to about 10 poise as measured on a cone and plate viscometer or between Spindle 1 at 100 centipoise and spindle 7 at 30,000 centipoise, each measured at about 20 °C. The use of a low viscosity composition is particularly advantageous when the substrate to be treated is porous in nature. The inventors have found that the low viscosity nature of the composition allows penetration into porous substrates, increasing the lifespan of the product and the surface it is protecting.

The carbon nanotubes (component (a)) are typically present in the compositions of the invention in an amount of up to about 5% by weight, for example up to about 2% by weight, or up to about 1 % by weight, such as from about 0.001% to about 0.1% by weight, or from about 0.005 to about 0.08% by weight, or from about 0.008 to about 0.05% by weight, for example about 0.01% by weight, relative to the total weight of the liquid composition.

Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure. The nanotubes used in this invention may, for example, have a length-to-diameter ratio of up to about 132,000,000:1 , such as from about 10:1 to about 1 ,000:1 or about 50:1 to about 500:1 , or from about 100:1 to about 200:1 , for example about 150:1 to about 160:1 , such as about 158:1 or about 1500:9.5.

Carbon nanotubes are members of the fullerene structural family. They have a long, hollow structure with the walls formed by one-atom-thick sheets of carbon (graphene). Carbon nanotubes can be categorized as single-walled nanotubes (SWNTs) and multi- walled nanotubes ( WNTs). Either type of nanotube can be used in the present invention. In one aspect, multi-walled nanotubes are used. In another aspect, single- walled nanotubes are used.

An example of carbon nanotubes that are particularly suitable for use in the present invention is single-walled carbon nanotubes having a length-to-diameter ratio of from about 100: 1 to about 200: 1 , for example about 150: 1 to about 160: 1. Carbon nanotubes suitable for use in the present invention are available commercially. An example of commercially available carbon nanotubes that may be used in the present invention is multi-walled carbon nanotubes sold under the trade name Nanocyl NC7000 sold by Nanocyl (Belgium). It is appreciated that commercially available carbon nanotubes may contain small amounts of unidentified impurities. It is thought that these impurities do not affect the properties of the carbon nanotubes or the way in which the carbon nanotubes function in the present invention. It will be appreciated by the skilled reader that it is not possible to separate carbon nanotubes from these impurities and that it is unnecessary to do so. For the avoidance of doubt, if the phrase "consisting of or "consists of is used in the context of this invention it will be appreciated that the carbon nanotubes may include these impurities.

In an aspect of the invention the weight ratio of the fluorinated polyurethane or urethane polymer modified with perfluoroalkylsulfonamide (component (b)) to the carbon nanotubes (component (a)) is from about 10:1 to about 1000:1 , such as from about 20:1 to about 500:1 or from about 40:1 to about 250:1. Preferably the ratio of component (b) to component (a) is from about 50:1 to about 100:1 , such as about 80:1.

The compositions of the invention may also include ingredients that impart additional properties on the compositions of the invention. For example, the compositions of the invention can contain anti-fungal, anti-algae or anti-microbial ingredients.

In one aspect, the composition of the invention may contain anti-microbial ingredients such as quaternary ammonium compounds and/or antimicrobial compositions comprising quaternary ammonium compounds. Examples of antimicrobial compositions that may be used in the present invention include those sold by Byotrol PLC.

It will be appreciated that the formulations of the invention can comprise other ingredients commonly used in the art. The nature of any other ingredients used will depend on the nature and intended purpose of the formulation. The person of ordinary skill in the art will know which additional ingredients are suitable for use in formulations for different applications. Additional ingredients that may be used in the formulations of the invention include but are not limited to water, antioxidants, thickeners, corrosion inhibitors, foam makers and breakers, abrasives, sodium chloride, acids such as citric acid, colorants/dyes, fragrances and flow agents and flow modifiers.

The present invention also provides a process for preparing the compositions of the invention. This process comprises:

1. Mixing component (b), and optionally component (e), in the majority of the solvent (including any coalescent solvent) under low shear conditions. In this context, by "majority" we mean 70% or more, such as 75% or more or 80% or more, such as about 82%. An example of a suitable low shear mixing method that may be used is utilizing a high speed stirrer with a mixing dispersion blade at low shear speed. This step is typically carried out at about 15 to about 25 °C, for example room temperature (about 20 °C). The resulting product is a homogeneous mixture of the solvent and the hydrophobic material. Typically, it is not necessary to include an emulsifier in the compositions of the invention and component (b), and optional component (e), is typically miscible in the solvent.

2. Dispering the carbon nanotubes in the remaining solvent. This step can be conducted using an ultrasonic mixer. This step is typically carried out at about 15 to about 25 °C, for example room temperature (about 20 °C). However, heat may be generated during the mixing process, so cooling may be necessary. The use of super high energy sonification equipment in this step facilitates the creation of a "super dispersion", that is a dispersion that is homogenous and does not contain 'clumps' of material that may be present if standard mixing techniques are used.

3. Adding the mixture produced in step 2 slowly to the mixture from step 1 , with stirring. High shear conditions must be avoided during this step, this can be achieved by utilizing a high speed stirrer with a mixing dispersion blade at low shear speed. Alternative stirring methods that are suitable include other low shear mixing techniques such as air stirring or hydraulic stirrers with dispersion or mixing blades. This step is typically carried out at about 15 to about 25 °C, for example room temperature (about 20 °C). The present invention also provides the use of a composition of the invention as a coating material and articles that have been coated with a composition of the invention. If the resin binder is an additional ingredient to component (b), the resin binder is also added at the beginning of step one. As an example, the coalescent, resin binder and hydrophobic agent (in that order) could be mixed with any other solvent in a vessel utilizing a high speed stirrer with a mixing dispersion blade at low shear speed. In some instances the resin used could be in hard form. If that was the case the resin would be dissolved in the solvent first without component (b), and then component (b) and the mixture from step 2 would be added.

The compositions of the invention can be incorporated into compositions, such as paints, varnishes, lacquers, that are intended to be used to coat a substrate. The compositions of the invention can also be used to provide an "invisible" coating. That is a coating that alters the properties of a substrate and/or provides protection to the substrate without altering the appearance of the substrate. In use, a composition of the invention is applied to a substrate to be coated.

Suitable substrates include hard surfaces such as wood, plaster, brick, plastics, glass laminates, clays, china, ceramics, concrete, some fabrics, sandstone and fiberboard. The compositions of the invention can, for example, be used on BBQ areas, grouting, greenhouses, window frames, slate roofing, tiled walls and floors, pool surrounds, doors, garden furniture, some types of painted walls and painted surfaces, (such as some paint emulsion types), rendering, pebbledash, caravan areas, garden sheds and industrial stone productions. Substrates on which the compositions of the invention could be used include, but are not limited to institutional and domestic showers, monuments and historic buildings, stone lintels, thatched roofs, marine canvas, natural timber and other substrates the appearance of which may be spoiled or altered if they looked painted or varnished. Thus, in one aspect, the present invention provides a composition for coating a hard surface and the use of the composition of the invention to coat a hard surface.

It is not envisaged that the compositions of the invention will be used on soft surfaces such as fabric surfaces.

The compositions of the invention can also be used to reduce or prevent flood damage and/or to reduce or prevent heat loss (for example by preventing water ingress hence preventing evaporative cooling). The compositions of the invention can be applied to a substrate using any suitable technique. Suitable techniques include application with a brush or roller, spraying, such as high pressure or low pressure spraying, curtain coating and immersion in a composition of the invention. The composition of the invention may be provided in a ready to use form or in the form of a concentrate that is to be diluted by the user at the point of use, by the use of a suitable diluent, for example, water. In an aspect of the invention, if the composition is supplied in the form of a concentrate then component (a) may be present in an amount of up to about 10% by weight, for example up to about 4% by weight, or up to about 1 % by weight, such as from about 0.002% to about 0.2% by weight, relative to the total weight of the concentrated composition; component (b) may be present in an amount of from about 0.5 to 80% by weight, for example from 2 to 55% by weight, more preferably from 3 to 45% by weight, relative to the total weight of the liquid composition; and component (c) may be present in an amount of from about 1 to about 30% by weight of the composition, such as from about 2 to about 20% by weight of the composition or from about 4 to about 16% by weight, relative to the total weight of the liquid composition.

If necessary, the viscosity of a composition of the invention can be adjusted by altering the amount of solvent present in the composition.

Once the composition of the invention has been applied to the substrate it dries onto the substrate. This drying step is typically conducted at ambient temperature (for example from about 0 °C to about 40 °C, typically at about 15 °C to about 25 °C, such as at room temperature). Methods to enhance drying such as increasing the temperature or increasing air flow can be used, if desired.

The film formed by the drying of a composition of the invention is typically touch dry within an hour of application, such as within 30 minutes of application and completely dry within 48 hours of application, such as within 24 hours.

Without wishing to be bound by theory, it is thought that the drying process is coalescent in nature, such that the binder particles are drawn together and fuse together into irreversible bound networked structures. As a result, the coating or film formed on the surface does not re-dissolve in the solvent/water that originally carried it or on application of water.

Brief description of the Figures:

The photographic results from Examples 1 to 3 are shown in Figures 1 to 6, the photographic results of Example 4 to 6 are shown in Figures 7 to 9. Figure 10 shows in pictorial form how the contact angle of liquid on a surface is measured. The photographic results of Example 7 are shown in Figures 1 1 to 16. Each figure is described in detail below.

Figure 1 : Figure 1A shows results obtained directly after application of vegetable oil and water on Portland stone treated with two brush coats of formula MR. Figure 1 B shows results obtained 24 hours after application after attempted removal of excess liquid.

Figure 2: Figure 2A shows results obtained directly after application of vegetable oil and water on Portland stone treated with two brush coats of formula CNTMR. Figure 2B shows results obtained 24 hours after application after attempted removal of excess liquid.

Figure 3: Figure 3A shows results obtained directly after application of vegetable oil and water on untreated Portland stone. Figure 3B shows results obtained 24 hours after application after attempted removal of excess liquid.

Figure 4: Figure 4A shows results obtained directly after application of vegetable oil and water on York stone treated with two brush coats of a formula MR. Figure 4B shows results obtained 24 hours after application after attempted removal of excess liquid.

Figure 5: Figure 5A shows results obtained directly after application of vegetable oil and water on York stone treated with two brush coats of formula CNTMR. Figure 5B shows results obtained 24 hours after application after attempted removal of excess liquid. Figure 6: Figure 6A shows results obtained directly after application of vegetable oil and water on untreated York stone. Figure 6B shows results obtained 24 hours after application after attempted removal of excess liquid.

Figure 7: Figure 7A shows results obtained directly after application of vegetable oil and water on Portland stone treated with two brush coats of formula MR, which had been subjected to 250 hours QUV. Figure 7B shows results obtained 24 hours after application after attempted removal of excess liquid.

Figure 8: Figure 8A shows results obtained directly after application of vegetable oil and water on Portland stone treated with two brush coats of formula CNTMR, which had been subjected to 250 hours QUV. Figure 8B shows results 24 hours after application after attempted removal of excess liquid. Figure 9: Figure 9A shows results obtained directly after application of vegetable oil and water on untreated Portland stone, which had been subjected to 250 hours QUV. Figure 9B shows results obtained 24 hours after application after attempted removal of excess liquid.

Figure 10: Shows how the contact angle of liquid on a surface was measured.

Figure 11 : Shows the results obtained on an untreated block paver when challenged with dirty engine oil, vegetable oil, red wine and soy sauce immediately after the challenge, 24 hours after the challenge and after cleaning with cold water.

Figure 12: Shows the results obtained on a block paver treated with Aspira when challenged with dirty engine oil, vegetable oil, red wine and soy sauce immediately after the challenge, 24 hours after the challenge and after cleaning with cold water.

Figure 13: Shows the results obtained on a block paver treated with Thompsons Water Seal when challenged with dirty engine oil, vegetable oil, red wine and soy sauce immediately after the challenge, 24 hours after the challenge and after cleaning with cold water.

Figure 14: Shows the results obtained on a block paver treated with Thompsons One Coat Patio Seal when challenged with dirty engine oil, vegetable oil, red wine and soy sauce immediately after the challenge, 24 hours after the challenge and after cleaning with cold water.

Figure 15: Shows the results obtained on a block paver treated with Ronseal One Coat Concrete Seal when challenged with dirty engine oil, vegetable oil, red wine and soy sauce immediately after the challenge, 24 hours after the challenge and after cleaning with cold water.

Figure 16: Shows the results obtained on a block paver treated with Cementone Water Seal when challenged with dirty engine oil, vegetable oil, red wine and soy sauce immediately after the challenge, 24 hours after the challenge and after cleaning with cold water.

The invention will now be illustrated by the following non-limiting Examples. Comparative Testing: Experiments to demonstrate the advantageous properties of compositions of the invention compared to similar compositions that did not contain carbon nano-tubes.

Repellent Qualities

Example 1

Three fresh panels of York stone and three fresh panels of Portland stone were prepared as follows:

1) One panel of York stone and one panel of Portland stone were treated with 2 brush coats of a repellent formula that did not contain any carbon nano-tubes

(MR) with the following compositional formula:

Butyl Glycol 62.638%

Water 20.914%

SRC-220 16.448%

2) One panel of York stone and one panel of Portland stone were treated with 2 brush coats of a formula of the invention including the carbon nano-tubes

(CNTMR), prepared via the method described herein, with the following compositional formula:

Butyl Glycol 62.572%

Water 20.892%

SRC-220 16.430%

Carbon nanotubes solution 0.106%

3) One panel of York stone and one panel of Portland stone were left as untreated control panels (control).

Each treated stone panel was allowed to cure for a minimum of 24 hours.

Each of the panels was then challenged with a drop of vegetable oil and a drop of water (referred hereinafter as "the liquids"). The liquid was delivered using a pipette. The volume of liquid (either vegetable oil or water) added per challenge was approximately 0.1 ml.

Photographs of each of the panels were taken at the following stages:

1. Within 10 minutes of challenging with the liquids. 2. 24 hours after the liquid had been applied, and after attempts had been made to remove any excess liquid with the aid of an absorbent paper towel, wherein the surface was rubbed with a dry absorbent paper towel to try to remove any remaining stain. The photographs (as shown in Figures 1 to 6) were then used to ascertain the repellent qualities of the formulas by measurement of the spread of the liquid and the spread of any stain after removal of the liquid.

All the substrate panels were numbered and the measurement point is indicated in the photograph by the relevant suffix and the following measurement scale was used:

0. No stain/completely evaporated

1. Very light Stain

2. Light Stain

3. Moderate Stain

4. Heavy Stain or liquid visible as a repelled globule and not necessarily staining

The spread of the liquid and of the stain was measured as an area approximated to a circle as follows:

π x (Height (mm) x Width (mm)/2) x (Height (mm) x Width (mm)/2)

The results obtained are shown in the tables below.

Vegetable oil on York stone

Example 2

Three fresh panels of Portland stone were prepared as in Example 1.

After the treated stone panels had been allowed to cure for at least 24 hours, all of the panels were subjected to 250 hours within a QUV test apparatus (Q-Lab - model QUV/SE using B Tubes (313 nanometers)). The QUV accelerated weathering procedure reproduces the damage caused by sunlight, rain and dew. In a few days or weeks, the QUV UV tester can reproduce the damage that occurs over months or years outdoors.

After the accelerated weathering procedure the panels were challenged with liquids described in Example 1.

Photographs were then taken at the following stages:

1. Within 10 minutes of challenging with the liquids.

2. 24 hours after the liquid had been applied, and after attempts had been made to remove any excess liquid with the aid of an absorbent paper towel wherein the surface was rubbed with a dry absorbent paper towel to try to remove any remaining stain. The photographs (as shown in Figures 7 to 9) were then used to ascertain the repellent qualities of the formulas by measurement of the spread of the liquid and the stain after removal of the liquid as performed in Example 1.

The results obtained are shown in the tables below

Example 3

Three fresh panels of Portland stone and three fresh panels of York stone were prepared as in Example 1.

After the treated stone panels had been allowed to cure for at least 24 hours, all of the panels were subjected to 500 hours within a QUV test apparatus (Q-Lab - model QUV/SE using B Tubes (313 nanometers)). After the accelerated weathering procedure the panels were challenged with water as described in Example 1.

The results obtained are shown in the tables below. Water on Portland stone - 500 hour QUV

Immediate Immediate 24 Hour 24 Hour

Position Rank Stain Spread Stain Spread

CNTMR 4 154 0 0 1 1

MR 4 201 0 0 1 2

Control 4 2,552 0 0 3 3

Water on York stone - 500 hour QUV

Immediate Immediate 24 Hour 24 Hour

Position Rank Stain Spread Stain Spread

CNTMR 4 227 0 0 1 1

MR 4 255 0 0 1 2 Control 4 2,124 0 0 3 3

Conclusion

The two formulas tested under QUV for a total of 500 hours displayed repellency properties but the CNTMR outperformed the MR.

Contact Angle: A comparative test to investigate the ability of the composition of the invention (CNTMR) to maintain their hydrophobic qualities compared to a composition which did not contain carbon nano-tubes (MR).

A surface is considered hydrophobic when the contact angle is above 90 degrees.

Contact angle is measured in accordance with the diagram in Figure 10 using a modification of the Young Equation, assuming that the surface has none ideal rough solid surfaces but standardising on a defined surface structure.

The substrates chosen for the comparative contact angle tests were Portland stone and York stone.

Example 4

Two fresh panels of York stone and two fresh panels of Portland stone were prepared as followed: 1) One panel of York stone and one panel of Portland stone were treated with 2 brush coats of a repellent formula that did not contain any carbon nano-tubes

(MR) with the following compositional formula:

Butyl Glycol 62.638%

Water 20.914%

SRC-220 16.448%

2) One panel of York stone and one panel of Portland stone were treated with 2 brush coats of a formula of the invention including the carbon nano-tubes (CNTMR), prepared via the method described on page 10, line 16 to page 11 , line 9 of the application, with the following compositional formula:

Butyl Glycol 62.572%

Water 20.892%

SRC-220 16.430%

Carbon nanotubes solution 0.106%

Each treated stone panel was allowed to cure for a minimum of 24 hours.

Each of the panels was then challenged with a drop of water.

The volume of liquid added per challenge was approximately 0.1 ml and applied using a pipette.

The contact angle of the liquid droplet was then determined. Example 5

Three fresh panels of York stone and three fresh panels of Portland stone were prepared as in Example 4. After the treated stone panels had been allowed to cure for at least 24 hours, all of the panels were subjected to 250 hours within a QUV test apparatus (Q-Lab - model QUV/SE using B Tubes (313 nanometers)).

The QUV accelerated weathering procedure reproduces the damage caused by sunlight, rain and dew. In a few days or weeks, the QUV UV tester can reproduce the damage that occurs over months or years outdoors.

After the accelerated weathering procedure the panels were challenged with liquids as described in Example 4. The contact angle of the liquid droplet was then determined. Example 6

The panels prepared in Examples 5 were then subjected to an additional 250 hours (total 500 hours total) within a QUV test apparatus. After the accelerated weathering procedure the panels were challenged with liquids as described in Example 4.

The contact angle of the liquid droplet was then determined.

Results

Conclusion

The test results show that when the liquid was applied to a surface that had been treated with CNTMR that had been subjected to 500 QUV hours, the liquid had a contact angle of greater 90 degrees contact angle. On the other hand, when the liquid was applied to a surface that had been treated with MR that had been subjected to 5000 QUV hours the liquid had a contact angle of less than 90 degrees. This illustrated that improved properties of the compositions of the invention.

Comparative Testing: Experiments to demonstrate the advantageous properties of the compositions of the invention compared to compositions that do not contain carbon nano-tubes and/or a fluorinated polyurethane or urethane polymer modified with perfluoroalkylsulfonamide.

Example 7

Six fresh block pavers were prepared as follows:

1 ) One block paver was left as an untreated control (control)

2) One block paver was treated with Aspira Stain Repel (a composition of the invention). 3) One block paver was treated with Thompsons Water Seal, which is a composition that comprises an alkyl polysiloxane resin, (this is from the Thompsons product data sheet)

4) One block paver was treated with Thompsons One Coat Patio Seal, which is a composition that comprises acrylic resins in aromatic hydrocarbon solvents (this is from the Thompsons product data sheet). 5) One block paver was treated with Ronseal One Coat Concrete Seal, which is a composition that comprises acrylic solvents, (from Ronseal data sheet)

6) One block paver was treated with Cementone Water Seal, which is a composition that comprises polyoxo aluminium stearate (from data sheet).

Each treated stone panel was allowed to cure for a minimum of 24 hours.

Photographs of each of the panels were taken at the following stages: 1. Within 2 minutes of challenging with the liquids.

2. After the gross debris is removed with a paper towel 24 hours after the liquid had been applied. 3. Between 24 and 26 hours after the liquid has been applied, after the excess liquid has been removed and the surface rubbed dry with an absorbent paper towel to try to remove any remaining stain with cold water.

The photographs (as shown in Figures 11 to 16) were then used to ascertain the repellent qualities of the formulas by measurement of the spread of the liquid and the spread of any stain after removal of the liquid. All the substrate panels were numbered and the measurement point is indicated in the photograph by the relevant suffix and the following measurement scale was used:

0. No stain/completely evaporated

1. Very light Stain

2. Light Stain

3. Moderate Stain

4. Heavy Stain or liquid visible as a repelled globule and not necessarily staining The spread of the liquid and of the stain was measured as an area approximated to a circle as follows:

π x (Height (mm) x Width (mm)/2) x (Height (mm) x Width (mm)/2) The results obtained are shown in the table below.

24 Hours After Challenge

Immediately After

and removal of gross After Cleaning

Challenge

debris

Thompsons Water Seal

Treated

Block Paver

Dirty Engine Oil ₄ 133 3 755 3 755 2264.6

4 299 4 1105 4 1164 4657.2

Vegetable Oil ^{Si St}rancoe 1835.1

Red Wine 4 123 3 123 2 123 245.5

4 87 3 87 2 87 173.2

Soy Sauce

^{S Sit}reanco

^{S Sitr}eanco

d C^{b Si}coreneom d C^{b Si}co^reomne

331.5

Red Wine 4 57 3 57 2 57 113.5

4 71 1 95 1 64 63.6

Soy Sauce

Conclusion The Aspira treatment provided better protection than the to the competitor products tested, showing that the combination of the carbon nanotubes with the f!uorinated po!yurethane or urethane polymer modified with perfiuoroaikylsulfonamide provides improved repellent properties compared to compositions that do not contain this

combination of ingredients.

Fungal/Algal Challenge Example 8 20 aluminium sheet squares were painted with the following compositions:

1) 2 x HMG paint + 2% Promex FPD + Aspira

2) 2 x HMG paint + 0.5% Promex FPD + Aspira

3) 2 x HMG paint + 2% Promex FPD

4) 2 x HMG paint + 1% Promex FPD + Aspira 5) 2 x HMG paint + 0.3% an antimicrobial composition supplied by Byotrol PLC

6) 2 x HMG paint + 1 % Promex FPD

7) 2 x HMG paint + Aspira

8) 2 x HMG paint + 0.3% an antimicrobial composition supplied by Byotrol PLC + Aspira

9) 2 x HMG paint + 0.5% Promex FPD 10) 2 x HMG paint Each of the painted aluminium squares were then sanitized by UV (10 W UVC) for 30 minutes using a Germix ST Y -9001 machine. 10 of the painted aluminium squares were placed on a fungal growth promoting agar dish (Sabauroud Dextrose Agar (SDA) petri dishes) and a fungal spore suspensions of common fungal contaminants (1 x 10⁴ cfu ml^"1) was applied based on ASTM 5590 "standard test method for determining the resistance of paint films and related coatings to fungal defacement by accelerated four week plate assay". Growth on the squares was assayed visually (percentage covered) at 2 weeks and 4 weeks.

10 of the painted aluminium squares were placed on a algal growth promoting agar dish (Bolds Basal Media (Sigma Aldrich)) and a fungal spore suspensions of common fungal contaminants (0.2 ml) was applied based on ASTM 5589 "standard test method for determining the resistance of paint films and related coatings to algal defacement". Growth was checked for up to 28 days.

The results obtained are shown in the Table below:

Conclusion

The HGM paint on its own was suseptible to algal growth, however the samples that contained the Aspira compositoin of the invention showed no algal or fungal growth.

Claims

Claims:

1. A liquid coating composition comprising:

(a) carbon nanotubes;

(b) a fluorinated polyurethane or a urethane polymer modified with a perfluoroalkylsulfonamide;

(c) a resin binder; and

(d) a solvent;

wherein an ingredient may be both component (b) and component (c) or component (b) and component (c) may independently be separate ingredients.

2. A composition according to claim 1 , wherein the composition optionally comprises

(e) at least one silicone and/or at least one siloxane.

3. A composition according to claim 1 or 2, wherein the urethane polymer modified with a perfluoroalkylsulfonamide is obtainable by the reaction of at least 20% of the nitrogen atoms in the urethane monomers or at least 20% of the nitrogen atoms in the pre-formed urethane polymer with a compound of the following general formula:

wherein n is from 1 to 20, such as from 2 to 10, 2 to 4, or 6.

4. A composition according to claim 2, wherein the at least one silicone has the formula:

wherein A and B are each independently a hydrocarbon group containing from 1 to 12 carbon atoms and n and m are independently integers of from 1 to 24.

5. A composition according to claim 2, wherein the at least one siloxane has the formula (H₃C)[SiO(CH₃)2]nSi(CH₃)3, and/or (H₃C)[SiO(CH3)H]nSi(CH₃)3 where n is an integer, of from 1 to 24.

6. A composition according to any one of the preceding claims, wherein component (c) does not satisfy the definition of component (b).

7. A composition according to any one of claims 1 to 5, wherein component (c) satisfies the definition of component (b).

8. A composition according to claim 6, comprising a resin binder ingredient selected from alkyds, acrylics, vinyl-acrylics, vinyl acetate/ethylene (VAE), polyurethanes, polyesters, melamine resins, epoxy, oils and mixtures thereof.

9. A composition according to any one of the preceding claims additionally comprising a coalescent solvent.

10. A composition according to any one of the preceding claims, wherein the carbon nanotubes have a length-to-diameter ratio of from about 50:1 to about 500:1.

11. A composition according to any one of the preceding claims, wherein the carbon nanotubes are single-walled carbon nanotubes.

12. A composition according to any one of the preceding claims, wherein the solvent comprises at least one polar solvent.

13. A composition according to claim 12, wherein the solvent is water, optionally in combination with an alkyl ether or ethylene glycol.

14. A composition according to any one of the preceding claims, wherein the weight ratio of the fluorinated polyurethane or urethane polymer modified with perfluoroalkylsulfonamide (component (b)) to the carbon nanotubes (component (a)) is from about 10:1 to about 1000:1.

15. A composition according to any one of the preceding claims additionally comprising an anti-fungal, anti-algae or anti-microbial ingredient.

16. A process for producing a composition as defined in any one of the preceding claims, the process comprising:

(i) mixing component (b), and optionally component (e), in at least 70% of the solvent under low shear conditions to produce a homogeneous mixture of the solvent and component (b), and optionally component (e);

(ii) dispersing the carbon nanotubes in the remaining solvent under ultrasonic conditions; and

(iii) adding the mixture produced in step (ii) to the mixture from step (i), with stirring.

17. A coating obtainable by drying a composition according to any one of claims 1 to 15.

18. A coated substrate obtainable by applying a composition as defined in any one of claims 1 to 15 to at least one surface of the substrate and allowing the composition to dry.

19. A hard surface coating composition according to any one of claims 1 to 15.

20. The use of a composition as defined in any one of claims 1 to 15 to coat a hard surface.

21. A process for coating a surface comprising applying a composition as defined in any one of claims 1 to 15 to the surface.

22. A process according to claim 21 , wherein the surface is a hard surface.