Patent Application
20080090004
As used herein, by “hydrophobic nano-sized particles” it is meant particles that are hydrophobic and have a diameter in the nano-scale range (i.e. from 1 nm to 1000 nm). As will be apparent to a person skilled in the art, hydrophobic nano-sized particles have non-polar groups on the surface of the particles. As will also be apparent to a person skilled in the art, the surface of a hydrophobic nano-sized particle may contain some hydrophilic groups, such as hydroxyl groups, provided that the surface contains more non-polar groups than hydrophilic groups.
Preferably the hydrophobic nano-sized particles have an average particle size in the range of from 1 nm to 500 nm, more preferably from 1 nm to 50 nm, and even more preferably from 1 nm to 10 nm.
Preferably 5% or more of the non-polar groups on the surface of the nano-sized particles in the composition are fluoro-substituted non-polar groups. In some embodiments, 10% or more of the non-polar groups are fluoro-substituted non-polar groups. In some embodiments, fluoro-substituted non-polar groups may comprise up to 30% or 40% of the non-polar groups on the surface of the nano-sized particles.
Typically the hydrophobic nano-sized particles are nano-sized particles prepared by Reaction 1 or Reaction 2.
The hydrolysis and condensation of one or more compounds of formula (A), optionally together with one or more compounds selected from compounds of the formula (B) and compounds of formula (C), to form hydrophobic nano-sized particles (Reaction 1) is a sol-gel reaction.
The sol-gel reaction consists of two main reactions:
Hydrolysis: in which an alkoxy group of a compound of formula (A) (or a compound of formula (B) or (C)) is hydrolysed (as shown in Scheme 1 below for reactions in which M is Si); and
Condensation: in which the hydrolysed compound of formula (A) (or hydrolysed compound of formula (B) or (C)) reacts with another optionally hydrolysed compound of formula (A) (or optionally hydrolysed compound of formula (B) or (C)) to form a covalently bonded network (Scheme 2a or 2b below for reactions in which M is Si).
These two reactions are usually concurrent. The reaction results in the formation of a covalently bonded network.
The resultant covalently bonded network is a nano-sized particle with non-polar groups R1 located on the surface of the particle. The surface of the particle typically also includes some hydroxyl groups (from the hydrolysis of the OR groups).
In some embodiments, the nano-sized covalently bonded networks formed are joined together in the form of a covalently bonded network of hydrophobic nano-sized particles.
In formulas (A), (B), (C), (1) and (2), R is typically a C1-10 alkyl, for example methyl, ethyl, propyl, etc.
In formulas (A), (1) and (2), M is typically Si, Ti or Zr, more typically Si. In formula (B), M is typically Si, Ti, Al or Zr. In formula (C), M may for example be Al or Zn. Compounds of formula (C) include, for example, compounds of the formula R1Al(OR)2 or R1Zn(OR). In formulas (B) and (C), the integers m and n depend on the valence of the metal.
In formulas (A) and (C), R1 may be any non-polar group. R1 is typically C1-10 alkyl, C2-10 alkenyl, phenyl, an epoxy group, an acrylate group or an isocyanate group.
The compound of formula (A) may for example, be an alkyltrialkoxysilane, such as methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane or ethyltriethoxysilane; a vinyltrialkoxysilane such as vinyltrimethoxysilane; an epoxyl trialkoxysilane such as (3-glycidoxypropyl)trimethoxysilane; an acrylate trialkoxysilane such as methacrylate trimethoxysilane; or an isocyanate trialkoxysilane such as triethoxy(3-isocyanatopropyl)silane.
In formulas (A) and (C), R1 may be a fluoro-substituted non-polar group, for example, a fluoro-substituted C3-10 alkyl or phenyl group. R1 may, for example, be a multiply fluoro-substituted group, preferably a perfluoro-substituted group. R1 may for example be 1H,1H,2H,2H-perfluoro-octyl, 1H,1H,2H,2H-perfluoro-decyl, 3,3,3-trifluoro-propyl or pentaflurophenyl.
The compound of formula (B) may for example be a tetraalkoxysilane, such tetraethyl orthosilicate (Si(OCH2CH3)4) or tetramethyl orthosilicate (Si(OCH3)4).
In some embodiments of the present invention, the hydrophobic nano-sized particles are hydrophobic nano-sized particles prepared by the hydrolysis and condensation of one or more compounds of formula (1) as defined above with one or more compounds of formula (2) as defined above. In such embodiments of the present invention, the weight ratio of the compounds of formula (1) to the compounds of formula (2) used to prepare the nano-sized particles is typically from about 1:0.05 to about 1:1.
In some other embodiments of the present invention, the hydrophobic nano-sized particles are prepared by the hydrolysis and condensation of one or more compounds of formula (1) with one or more compounds of formula (2), together with one or more additional compounds selected from compounds of formula (B) and compounds of formula (C). In such embodiments of the present invention, the weight ratio of the compounds of formula (1) to the compounds of formula (2) used to prepare the nano-sized particles is typically from about 1:0.05 to about 1:1.
In formula (1), R2 may be any non-polar group that is not fluoro-substituted. R2 is typically C1-10 alkyl, C2-10 alkenyl, phenyl, an epoxy group, an acrylate group or an isocyanate group. The compound of formula (1) may for example, be an alkyltrialkoxysilane, such as methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane or ethyltriethoxysilane; a vinyltrialkoxysilane such as vinyltrimethoxysilane; an epoxyl trialkoxysilane such as (3-glycidoxypropyl)trimethoxysilane; an acrylate trialkoxysilane such as methacrylate trimethoxysilane; or an isocyanate trialkoxysilane such as triethoxy(3-isocyanatopropyl)silane.
In formula (2), R3 may be any fluoro-substituted non-polar group. Typically R3 is a fluoro-substituted C3-10 alkyl or phenyl group. Preferably, R3 is a multiply fluoro-substituted group, preferably a perfluoro-substituted group. R3 may for example be
The compound of the formula (2) is typically a multiply fluoro-substituted alkyltrialkoxysilane such as 1H,1H,2H,2H-perfluorooctyltriethoxysilane, 1H,1H,2H,2H-perfluorodecyltriethoxysilane, 3,3,3-trifluoro-propyltrimethoxysilane or pentafluorophenyl-triethoxysilane.
The hydrolysis and condensation of the one or more compounds of formula (1) with one or more compounds of formula (2), is typically carried out by preparing a reaction mixture comprising one or more compounds of formula (1), one or more compounds of formula (2), and an organic solvent, and exposing the reaction mixture to conditions effective to cause the compounds of formula (1) and (2) to undergo a hydrolysis and condensation reaction.
Similarly, the hydrolysis and condensation of the one or more compounds of formula (1) with one or more compounds of formula (2), together with one or more additional compounds selected from compounds of formula (B) and compounds of formula (C), is typically carried out by preparing a reaction mixture comprising one or more compounds of formula (1), one or more compounds of formula (2), one or more additional compounds selected from compounds of formula (B) and compounds of formula (C), and an organic solvent, and exposing the reaction mixture to conditions effective to cause the compounds of formula (1), the compounds of formula (2) and the one or more additional compounds to undergo a hydrolysis and condensation reaction.
In one embodiment, the present invention provides a method for forming a hydrophobic coating on the surface of a solid substrate, the method comprising:
In another embodiment, the present invention provides a method for forming a hydrophobic coating on the surface of a solid substrate, the method comprising:
The organic solvent is preferably a non-polar organic solvent. The organic solvent may for example be ethyl acetate, toluene, butyl acetate, hexane, heptane, xylene, methylethyl ketone, diethyl ether, telrahydrofuran or a mixture thereof. To initiate the hydrolysis and condensation reaction, a small amount of water must be present in the reaction mixture. Typically, the amount of water present in commercially available organic solvents is sufficient for this purpose. Alternatively, a small amount of water could be added to the reaction mixture.
Typically, the reaction mixture further comprises a catalyst to catalyse the reaction. Suitable catalysts include dibutyltin dilaurate or zinc octoate. The reaction mixture is typically heated to about 60° C. to form the nano-sized particles.
The hydrolysis and condensation reaction produces hydrophobic nano-sized particles. The resultant composition comprising the hydrophobic nano-sized particles in the organic solvent can be applied to the surface of the solid substrate without modification.
Alternatively, the resultant composition containing the nano-sized particles in the organic solvent may be mixed with other components, such as a curing agent, to form the composition applied to the surface.
The present inventors have found that when the hydrophobic nano-sized particles are prepared by Reaction 1, the polarity of the organic solvent influences the degree of hydrophobicity of the coating. Without wishing to be bound by theory, the inventors believe that when a non-polar solvent is used, the non-polar groups remain on the surface (pointing into the solvent phase) of the forming particle. Following removal of the solvent, for example during curing, those non-polar groups remain on the surface of the nano-sized particle, thus increasing the hydrophobicity of the particle and the resultant coating. For similar reasons, when a more polar solvent is used (for example an alcohol), the distribution of non-polar groups is reversed, with more hydrophilic groups (eg OH groups) pointing into the solvent phase, and the non-polar groups are buried inside the nano-sized particles formed by Reaction 1.
Advantageously, using a non-polar organic solvent, it is possible to concentrate the distribution of non-polar groups, including fluoro-substituted non-polar groups, on the surface of the nano-sized particles prepared by Reaction 1.
In some embodiments of the present invention, the hydrophobic nano-sized particles are prepared by the hydrolysis and condensation of one or more compounds of formula (3) with one or more compounds of the formula (2), and optionally with one or more additional compounds selected from compounds of formula (1), compounds of formula (B) and compounds of formula (C), to form nano-sized covalently bonded networks. This reaction may be carried out in the presence of water, a water-miscible organic solvent such as an alcohol, and a catalyst to catalyse the reaction. The organic solvent is a co-solvent to dissolve the one or more compounds of formula (2) and the one or more additional compounds, if any.
Accordingly, in one embodiment, the present invention provides a method for forming a hydrophobic coating on the surface of a solid substrate, the method comprising:
Typically the catalyst is dibutyltin dilaurate or zinc octoate. Typically the reaction mixture is heated to about 60° C. for about 3 hours to form the hydrophobic nano-sized particles in the form of a colloidal suspension.
Advantageously, the hydrolysis and condensation reaction of one or more compounds of formula (3) with one or more compounds of formula (2), and optionally with one or more additional compounds selected from compounds of formula (1), compounds of formula (B) and compounds of formula (C), can occur in a water based system. A water based system is generally more preferable than a process requiring the use of only organic solvents, as organic solvents can be more difficult to handle and have adverse environmental effects. The hydrolysis and condensation reactions result in the formation of a water based composition containing hydrophobic nano-sized particles. The resultant water based composition containing the hydrophobic nano-sized particles can, without modification, be applied to the surface of the solid substrate. Alternatively, the resultant water-based composition may be mixed with other components, such as a curing agent, to form the composition applied to the surface.
An advantage of some embodiments of the present invention is that the composition applied to the surface to form the coating is water based.
The Composition Comprising the Hydrophobic Nano-sized Particles
The composition applied to the surface of the solid substrate comprises hydrophobic nano-sized particles, wherein at least some of the hydrophobic nano-sized particles are particles having at least one fluoro-substituted non-polar group on the surface of the particle.
In a second aspect, the present invention provides a coating composition comprising hydrophobic nano-sized particles and an organic solvent, wherein the hydrophobic nano-sized particles are hydrophobic nano-sized particles formed by the hydrolysis and condensation of one or more compounds of formula (1) with one or more compounds of formula (2).
In a third aspect, the present invention provides a coating composition comprising hydrophobic nano-sized particles and an organic solvent, wherein the hydrophobic nano-sized particles are hydrophobic nano-sized particles formed by the hydrolysis and condensation of one or more compounds of formula (1) with one or more compounds of formula (2), together with one or more additional compounds selected from the group consisting of compounds of formula (B) and compounds of formula (C).
In a fourth aspect, the present invention provides a coating composition comprising hydrophobic nano-sized particles, water and a water-miscible organic solvent, wherein the hydrophobic nano-sized particles are hydrophobic nano-sized particles formed by the hydrolysis and condensation of one or more compounds of formula (3) with one or more compounds of formula (2), and optionally together with one or more additional compounds selected from the group consisting of compounds of formula (1), compounds of formula (B) and compounds of formula (C).
In some embodiments, the composition may further comprise a polymer capable of reacting with two or more of the hydrophobic nano-sized particles. Preferably, the polymer has hydrophobic properties. When the composition is a composition according to the second, third or fourth aspects of the present invention, the polymer may be included in the reaction mixture used to form the hydrophobic nano-sized particles, or may be added to the composition after the hydrophobic nano-sized particles have been formed.
The polymer is typically a siloxane polymer capable of reacting with hydroxyl groups on the surface of the particles and the surface of the solid substrate. Such siloxane polymers include hydroxy terminated polydimethylsiloxane (PDMS), hydroxy terminated polydiphenylsiloxane, hydroxy terminated polyphenylmethylsiloxane, hydroxy terminated polymethylhydrosiloxane, hydroxy terminated copolymers of methyl hydrosiloxane and dimethylsiloxane, vinylmethoxysiloxane homopolymer, polytrifluoropolymethylsiloxane (silanol terminated), copolymer of vinylmethylsiloxane and dimethylsiloxane (silanol terminated), polyvinylmethylsiloxane, polyepoxysiloxanes and polymethacrylatesiloxanes.
Typically the polymer is hydroxy terminated PDMS. Hydroxy terminated PDMS is capable of reacting with hydroxyl groups on the surface of the particles, changing the hydrophilic hydroxyl group to a hydrophobic group. By reacting with the hydroxyl groups on the surface of the particles, the polymer contributes to the hydrophobicity of the particles and thus the resultant coating. The reaction of the polymer with the particles may also link the particles together to form a gel comprising a network of particles linked by polymer strands. The composition applied to the surface in accordance with the method of the present invention may comprise such a gel.
Hydrophobic nano-sized particles prepared by the hydrolysis and condensation of one or more compounds of formula (A), optionally together with one or more compounds selected from compounds of formula (B) and compounds of formula (C) (Reaction 1), or prepared by the hydrolysis and condensation of one or more compounds of formula (3) with one or more compounds of formula (A), optionally together with one or more additional compounds selected from compounds of formula (B) and compounds of formula (C) (Reaction 2), are covalently bonded networks. The covalently bonded networks typically include some hydroxyl groups formed by the hydrolysis of the alkoxy groups in the compounds of formula (A), (B) and/or (C) used to prepare the covalently bonded networks. These hydroxyl groups are capable of undergoing a condensation reaction with hydroxyl groups on other particles or the surface of the solid substrate, thereby binding the particles together and to the surface in step (b) of the method of the present invention.
In some embodiments, a curing agent capable of reacting with the particles and the surface to link the particles together and to the surface is included in the composition. The curing agent may for example be 3-aminopropyltriethoxysilane. 3-aminopropyltriethoxysilane is capable of reacting with hydroxyl groups on the nano-sized particles and the surface to link the particles together and to the surface.
The solid substrate may be any solid substrate. Preferably, the surface of the solid substrate has micro-scale roughness. When a coating is formed on such a surface by the method of the present invention, the resultant coating typically has both nano-scale and micro-scale roughness. As a result of the combination of the nano-scale and micro-scale roughness of the coating, the coating is typically superhydrophobic.
The composition can be applied to the surface of the solid substrate by any means. The composition is applied to the surface in an amount sufficient to form a coating, typically a thin coating, of the hydrophobic nano-particles on the surface. The substrate may, for example, be wood, metal, stone, concrete or plastic.
The substrate may be a textile, such as a fabric, yarn or fibre. The textile may be made from any fibre, including natural fibres such as wool, silk, cashmere or cotton, synthetic fibres such as polyester or polypropylene, or a mixture of natural and synthetic fibres. The textile may be a woven or knitted fabric.
The substrate may also be a yarn or fibre. A yarn or fibre coated by the method of the present invention may be used to prepare a woven or knitted fabric.
When the substrate is a textile, the composition may, for example, be applied to the surface of the textile by dipping the textile into the composition, or by spraying the composition onto the surface of the textile. Dipping the textile into the composition applies a coating to all surfaces of the textile. By spraying the composition on to the surface of the textile, the method can be used to apply a coating to only one surface of the textile.
When the composition applied to the surface is a composition according to the second, third or fourth aspect of the present invention, and the composition comprises the curing agent 3-aminopropyltriethoxysilane, step (b) of the method of the present invention typically comprises exposing the applied composition to room temperature (e.g. 150 to 30° C.) for a time sufficient for the organic solvent or the water and the water-miscible organic solvent to evaporate, and for at least some of the particles to become linked together and to the surface to form a coating bound to the surface. When the composition applied to the surface is a composition according to the second, third or fourth aspects of the present invention, and the composition does not comprise a curing agent, step (b) typically comprises heating the applied composition to a temperature and for a time sufficient for the organic solvent or the water and the water-miscible organic solvent to evaporate and for at least some of the particles to become linked together and to the surface to form a coating bound to the surface. In some embodiments, the applied composition is heated to about 60° C.
In some embodiments, the hydrophobic nano-sized particles have non-polar groups on the surface of the particles that are capable of reacting with the surface of the substrate to further facilitate binding of the particles to the surface. For example, if the solid substrate is a textile made of polyethylene, and the hydrophobic nano-sized particles have vinyl groups on the surface of the particles, the vinyl groups are capable of reacting with the surface to bind the particles to the surface. Hydrophobic nano-sized particles having vinyl groups on the surface of the particles may for example be formed by Reaction 1 or Reaction 2 as described above in which the non-polar group R1 in one or more of the compounds of formula (A) or (C) used to prepare the hydrophobic nano-sized particle contains a vinyl group.
The present inventors have found that the methods and compositions of the present invention can be used to form a hydrophobic coating on textiles. The presence of the fluoro-substituted groups on the surface of the nano-sized particles provides the coating with resistance to wetting by oils and other solvents due to the low surface energy of such groups, and thus resistance to staining by oils and other solvents. The methods and compositions of the present invention can therefore be used to render a textile resistant to wetting by water and staining by oils and other solvents. In at least some embodiments, the method of the present invention can be used to render a textile resistant to wetting by water as well as resistant to staining by oils and other solvents, the textile being rendered resistant to staining by oils and other solvents using a lesser amount of fluorocarbons than some prior art fluorocarbon plasma treatment methods.
The surface of a textile typically has micro-scale roughness. When a coating is formed on the surface of a textile by the method of the present invention, the coated surface typically has both nano-scale and micro-scale roughness. As a result of the combination of the nano-scale and the micro-scale roughness of the coated surface, the coated surface is typically superhydrophobic.
In a preferred embodiment of the present invention, the solid substrate is a textile, and the composition comprises hydrophobic nano-sized particles produced by the hydrolysis and condensation of one or more compounds of formula (1) with one or more compounds of formula (2) where R3 is a multiply fluoro-substituted non-polar group, and the percentage by weight of the amount of the compounds of formula (2) to the compounds of formula (1) used to prepare the hydrophobic nano-sized particles is 5% or more. The coating on the textile formed by such a method is typically superhydrophobic and lyophobic. In another preferred embodiment of the present invention, the solid substrate is a textile and the composition comprises hydrophobic nano-sized particles produced by the hydrolysis and condensation of one or more compounds of formula (3) with one or more compounds of formula (2) where R3 is a multiply fluoro-substituted non-polar group, and the percentage by weight of the amount of the compounds of formula (2) to the amount of compounds of formula (3) used to prepare the hydrophobic nano-sized particles is 5% or more. The coating on the textile formed by such a method is typically superhydrophobic and lyophobic.
The present invention therefore provides a method that can be used to render the surface of a textile both superhydrophobic and lyophobic. The methods and coating compositions of the present invention can therefore be used to render the surface of textiles resistant to fouling by various substances such as dirt or microorganisms, and resistant to staining by oils and other solvents.
Advantageously, when the composition applied to the surface is a composition comprising hydrophobic nano-particles prepared by Reaction 1 or Reaction 2, and the composition does not contain other particulate material, the resultant coating is typically transparent or substantially transparent. Thus the method of the present invention can be used to render the surface of a textile superhydrophobic and lyophobic without substantially altering the visual appearance of the textile.
The invention is described below in more detail by reference to the following non-limiting examples.
In this example, a superhydrophobic and lyophobic coating was applied to various fabrics as described below.
A variety of coating compositions were prepared as described below.
The ingredients used to form the coating compositions are set out below:
A variety of coating compositions were prepared using the above ingredients in amounts within the ranges specified above. The coating compositions were prepared as follows: The methyltrimethoxysilane, 1H,1H,2H,2H-perfluorooctyltriethoxysilane, dibutyltin dilaurate and ethyl acetate were stirred at 60° C. for 3 hours. The resultant composition was then blended with 3-aminopropyltriethoxysilane to form the coating composition.
The coating compositions were then applied to various fabrics. The fabrics used were a pure wool fabric, a cotton/spandex (95/5) blended fabric, a silk fabric (100% silk), a wool/polyester (70/30) fabric, a polyester fabric, a polar fleece fabric and a polysafari suede fabric. The coating composition was applied to the pure wool fabric by dip coating using a padding machine, and applied to the other fabrics by spray coating. The applied composition was then cured at room temperature for at least 12 hours. The surface of the treated fabrics was superhydrophic and lyophobic.
A coated pure wool fabric was selected for a machine washing test to test the durability of the coating. The composition applied to the pure wool fabric used in the machine washing test was formed using the following amounts of the ingredients listed above:
The contact angle of water, a mixture of water and isopropanol comprising 90% by weight of water and 10% isopropanol (H2O/C3H7OH, 90/10), and a mixture of water and isopropanol comprising 75% by weight water and 25% isopropanol (H2O/C3H7OH, 75/25) on the coated pure wool fabric was measured using an automated contact angle goniometer made by Ramé-hart, Inc. after 1, 2 or 3 wash cycles using an accelerated washing test where 1 cycle is equal to 5 standard machine washes. The accelerated washing test used was AATCC test method 61-2001, and the instrument used was Atlas Launder-o-meter. The results are set out below.
The mixture of water and isopropanol has a lower surface energy than water, and is representative of other solvents having similar surface energies.
In this example, a superhydrophobic and lyophobic coating was applied to various fabrics as described below.
A variety of coating compositions were prepared as described below.
The ingredients used to form the coating compositions are set out below:
A variety of coating compositions were prepared using the above ingredients in amounts within the ranges specified above. The coating compositions were prepared as follows: The methyltrimethoxysilane, polydimethylsiloxane, 1H,1H,2H,2H-perfluorooctyltriethoxysilane, dibutyltin dilaurate and ethyl acetate were stirred at 60° C. for 3 hours. The resultant composition was then blended with 3-aminopropyltriethoxysilane to form the coating composition.
The coating compositions were then applied to various fabrics. The fabrics used were a pure wool fabric, a cotton/spandex (95/5) blended fabric, a silk fabric (100% silk), a wool/polyester (70/30) fabric, a polyester fabric, a polar fleece fabric and a polysafari suede fabric. The coating composition was applied to the pure wool fabric by dip coating using a padding machine, and applied to the other fabrics by spray coating. The applied composition was then cured at room temperature for at least 12 hours. The surface of the treated fabrics was superhydrophobic and lyophobic.
A coated pure wool fabric was selected for a machine washing test to test the durability of the coating. The composition applied to the pure wool fabric used in the machine washing test was formed using the following amounts of the ingredients listed above:
The contact angle of water, a mixture of water and isopropanol comprising 90% by weight of water and 10% isopropanol (H2O/C3H7OH, 90/10), and a mixture of water and isopropanol comprising 75% by weight water and 25% isopropanol (H2O/C3H7OH, 75/25) on the coated pure wool fabric was measured using an automated contact angle goniometer made by Ramé-hart, Inc. after 1, 2 or 3 wash cycles using a accelerated washing test where 1 cycle is equal to 5 standard machine washes. The accelerated washing test used was AATCC test method 61-2001, and the instrument used was Atlas Launder-o-meter. The results are set out below.
The effect of the solvent used during the formation of hydrophobic nano-sized particles by Reaction 1 on the hydrophobicity of the resultant coating is illustrated in the following example.
Two coatings were prepared using coating compositions A and B. The ingredients used to form the coating composition A are set out below:
The coating composition was prepared as follows: The methyltrimethoxysilane, 1H,1H, 2H, 2H-perfluorooctyltriethoxysilane, dibutyltin dilaurate and ethyl acetate were stirred at 60° C. for 3 hours. The resultant composition was then blended with 3-aminopropyltriethoxysilane to form the coating composition.
The coating composition was then applied to a piece of superfine wool fabric by dipping the fabric into the coating composition.
Coating composition B was prepared using a similar method, but using ethanol as the solvent. The ingredients used to form the coating composition B are set out below:
This coating composition was then applied to a piece of superfine wool fabric by dipping the fabric into the coating composition.
The water contact angle on the coated wool fabric is set out in Table 1.
This result indicates that when the hydrophobic nano-sized particles are formed by reactions of the type described as Reaction 1 above, the polarity of the organic solvent used can influence the degree of hydrophobicity of the coating.
In this example, a superhydrophobic and lyophobic coating was applied to various fabrics as described below.
A variety of coating compositions were prepared as described below.
The ingredients used to form the coating compositions are set out below:
A variety of coating compositions were prepared using the above ingredients in amounts within the ranges specified above. The coating compositions were prepared as follows: The potassium methyl siliconate, 1H,1H,2H,2H-perfluorooctyltriethoxysilane, dibutyltin dilaurate and water/alcohol mixed solvent were stirred at 60° C. for 3 hours. The resultant composition was then blended with 3-aminopropyltriethoxysilane to form the coating composition.
The coating compositions were then applied to various fabrics. The fabrics used were a pure wool fabric, a cotton/spandex (95/5) blended fabric, a silk fabric (100% silk), a wool/polyester (70/30) fabric, a polyester fabric, a polar fleece fabric and a polysafari suede fabric. The coating composition was applied to the pure wool fabric by dip coating using a padding machine, and applied to the other fabrics by spray coating. The applied composition was then cured at room temperature for at least 12 hours. The surface of the coated fabrics was superhydrophobic and lyophobic.
A coated pure wool fabric was selected for a machine washing test to test the durability of the coating. The composition applied to the pure wool fabric used in the machine washing test was formed using the following amounts of the ingredients listed above:
The contact angle of water, a mixture of water and isopropanol comprising 90% by weight of water and 10% isopropanol (H2O/C3H7OH, 90/10), and a mixture of water and isopropanol comprising 75% by weight water and 25% isopropanol (H2O/C3H7OH, 75/25) on the coated pure wool fabric was measured using an automated contact angle goniometer made by Ramé-hart, Inc. after 1, 2 or 3 wash cycles using a accelerated washing test where 1 cycle is equal to 5 standard machine washes. The accelerated washing test used was AATCC test method 61-2001, and the instrument used was Atlas Launder-o-meter. The results are set out below.
It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the Examples without departing from the spirit and scope of the invention. The Examples are therefore to be considered in all respects as illustrative and not restrictive.
In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004905746 | Oct 2004 | AU | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/AU05/01051 | 7/15/2005 | WO | 00 | 7/11/2007 |
