Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D1/00—Coating compositions, e.g. paints, varnishes or lacquers, based on inorganic substances
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D183/00—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon, with or without sulfur, nitrogen, oxygen, or carbon only; Coating compositions based on derivatives of such polymers
  • C09D183/04—Polysiloxanes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/16—Antifouling paints; Underwater paints
  • C09D5/1681—Antifouling coatings characterised by surface structure, e.g. for roughness effect giving superhydrophobic coatings or Lotus effect
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
  • C08K3/36—Silica
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K9/00—Use of pretreated ingredients
  • C08K9/04—Ingredients treated with organic substances
  • C08K9/06—Ingredients treated with organic substances with silicon-containing compounds

Definitions

• the present invention relates to a composition for applying to surfaces to create a hydrophobic coating thereon.
• the present invention relates to a composition comprising colloidal particle which is both partially hydrophobic and partially hydrophilic, a first hydrolyzed quaternary silane and solvent.
• compositions that result in such surfaces can be difficult to manufacture and can result in surfaces that display inferior self cleaning, a direct result, for example, of their characteristic contact angles that are too low. Moreover, reliable methods for generating superhydrophobic coatings that do not alter the look of treated surfaces are not a given.
• INTELLECTUAL PROPERTY LLC discloses a coating composition comprising a hydrophobic fumed silica ranging in size from 1000 to 4,000 nanometers, a solvent or solvent mixture selected from straight or branched, linear or cyclic aliphatic, or aromatic hydrocarbons with 2 to 14 carbon atoms, monovalent linear or branched alcohols with 1 to 6 carbon atoms, ketones or aldehydes with 1 to 6 carbon atoms, ethers or esters with 2 to 8 carbon atoms, or linear or cyclic polydimethylsiloxanes with 2 to 10 dimethylsiloxy units, in an effective amount of up to 50 percent by weight based on the total weight of the composition.
• the coating composition is said to be capable of rendering a superhydrophobic coating.
• compositions for generating such a coating are directed to a composition for yielding a hydrophobic coating comprising colloidal particle which is partially hydrophobic and partially hydrophilic, a first hydrolyzed quaternary silane and solvent.
• a composition for yielding a hydrophobic coating comprising colloidal particle which is partially hydrophobic and partially hydrophilic, a first hydrolyzed quaternary silane and solvent.
• Such a composition may comprise large amount of water and is typically capable of curing to yield a coating that is at least translucent and often transparent and/or which is durable.
• “Hydrophobic” for the purposes of the present invention is used to describe a molecule or portion of a molecule that is attracted to, and tends to be dissolved by oil (in preference to water), or a surface that has a contact angle against water of greater than 90°.
• “Ultrahydrophobic” as used herein means having a contact angle of at least 120° against water.
• “Superhydrophobic” as used herein means having a contact angle of at least 140° against water.
• Contact angle as used herein, means the angle at which a water/vapor interface meets a solid surface at a temperature of 25 °C. Such an angle may be measured with a goniometer or other water droplet shape analysis systems.
• Sliding angle as used herein, means the tilt angle of a surface at which a 5 ⁇ droplet of water slides at 25 °C.
• Olemer for the purposes of the present invention means a molecule that consists of several monomer units, for example, from 2 to 100, more preferably, from 2 to 60 monomer units. Hydrolysis
• Hydrolysis for the purposes of the present invention refers to a reaction with water.
• “Hydrolyzable” herein means the compound may react with water.
• “Hydrolyzed” means the compound is the reaction product of another compound (a precursor) with water.
• the weight of hydrolyzed silane as used herein refers to the weight of the hydrolyzed silane and its oligomers) (if have).
• pH values referred to herein are measured at a temperature of 25 °C.
• An uncoated glass slide having a transmittance of 89.0% is taken as substrate. Composition is spread on to one side of the slide to give an even coating of about 2.86 x
• the coating is cured for 10 minutes or until it forms a cohesive film.
• the coated slide is placed in a UV-vis spectrometer (e.g. Perkin-Elmer Lambda 650S) and the transmittance measured at 25 °C.
• a UV-vis spectrometer e.g. Perkin-Elmer Lambda 650S
• Transmittance is used herein as a measure of transparency and so should be determined in the absence of any chromophores with appreciable absorbance at 550 nm.
• Particle size as used herein refers to particle diameter unless otherwise stated.
• diameter means the z-average particle size measured, for example, using dynamic light scattering (see international standard ISO 13321) with an instrument such as a Zetasizer NanoTM (Malvern Instruments Ltd, UK).
• diameter means the apparent volume median diameter (D50, also known as x50 or sometimes d(0.5)) of the particles measurable for example, by laser diffraction using a system (such as a MastersizerTM 2000 available from Malvern Instruments Ltd) meeting the requirements set out in ISO 13320.
• Primary particle size refers to the diameter of particles in an unaggregated state.
• Refractive index is quoted at a temperature of 25 °C and a wavelength of 589 nm. Miscellaneous
• the present invention provides a composition comprising: a) colloidal particle;
• colloidal particle is both partially hydrophobic and partially hydrophilic, and the composition is capable of yielding a hydrophobic coating on a substrate.
• the present invention provides a method for forming a hydrophobic coating on a surface, the method comprising applying the composition of any embodiment of the first aspect to the surface and drying the composition to yield the hydrophobic coating.
• the present invention provides a hydrophobic coating obtained and/or obtainable by any embodiment of the method of the second aspect.
• the present invention provides a process for the preparation of the composition of any embodiment of the first aspect, wherein the process comprises the steps of:
• reaction mixture comprising water and a first quaternary silane precursor; ii. hydrolyzing the first quaternary silane precursor in the reaction mixture to provide a first hydrolyzed quaternary silane and/or its oligomer; and
• Colloidal particle often refers to single particle or aggregates of articles with primary particle size no greater than 1 micron.
• the colloidal particle suitable for use in the present invention is both partially hydrophobic and partially hydrophilic.
• the hydrophobicity or hydrophilicity of the colloidal particle may originate from the surface characteristics of the colloidal particle per se. However, it is preferred that the colloidal particle is both partially hydrophobically modified and partially hydrophilically modified.
• the colloidal particle preferably comprises at least one group selected from monovalent, linear or branched, saturated or unsaturated hydrocarbon radicals, monovalent fiuoro-substituted linear or branched, saturated or unsaturated hydrocarbon radicals, and at least one group selected from -OH, -SH, and -NH 2 . More preferably, the colloidal particle comprises at least one group selected from -Cf3 ⁇ 4 and -CF 3 , and at least one group selected from -OH, -SH, and -NH 2 . Even more preferably, the colloidal particle comprises -CT3 ⁇ 4 and at least one group selected from -OH and -NH 2 .
• the composition can still create a hydrophobic coating with inclusion of the colloidal particle of the present invention.
• the hydrophobicity of the coating may be due to the hydrophobicity of the particles, along with their structure afforded to the coating by the particles, and the capability of yielding hydrophobic coating even in present of over 50 wt% of water may be contributed from the hydrophilicity of the particles.
• An indicator of the surface hydrophobicity of colloidal particle is its relative diameter in a isopropanol/water solvent compared with pure isopropanol solvent, preferably the colloidal particle in a dispersion of 0.6 wt% of colloidal particle, 15.7 wt% of isopropanol, and 83.7 wt% of water, has number average diameter of greater than 2 times, more preferably greater than 3 times, even more preferably greater than 5, and most preferably greater than 10 times of number average diameter of the colloidal particle in dispersion of 0.6 wt% of colloidal particle and 99.4 wt% of isopropanol.
• the number average diameter of colloidal particle in dispersion of 0.6 wt% of colloidal particle, 15.7 wt% of isopropanol, and 83.7 wt% of water is preferably less than 10000 times, more preferably less than 1000 times, and even more preferably less than 100 times of the number average diameter of the colloidal particle in dispersion of 0.6 wt% of colloidal particle and 99.4 wt% of isopropanol.
• As an indicator of the surface hydrophilicity, when in a dispersion of 0.6 wt% of colloidal particle is preferably less than 10000 times, more preferably less than 1000 times, and even more preferably less than 100 times of the number average diameter of the colloidal particle in dispersion of 0.6 wt% of colloidal particle and 99.4 wt% of isopropanol.
• the colloidal particle preferably has number average diameter of less than 50 times, more preferably less than 30 times, even more preferably less than 15 times of number average diameter when the colloidal particle is in dispersion of 0.6 wt% of colloidal particle and 99.4 wt% of isopropanol.
• the number average diameter of colloidal particle in dispersion of 0.6 wt% of colloidal particle, 30.5 wt% of isopropanol, and 68.9 wt% of water is preferably greater than 1.5 time, more preferably than 2.5 times, and even more preferably than 5 times of the number average diameter of colloidal particle in dispersion of 0.6 wt% of colloidal particle and 99.4 wt% of isopropanol.
• the colloidal particle when in a dispersion of 0.6 wt% of colloidal particle, 0.07 wt% of hydrochloric acid, 30.5 wt% of isopropanol, and 68.83 wt% of water, the colloidal particle preferably has number average diameter of less than 30 times, more preferably less than 20 times, even more preferably less than 10 times of number average diameter when the colloidal particle is in dispersion of 0.6 wt% of colloidal particle and 99.4 wt% of isopropanol.
• the number average diameter of colloidal particle in dispersion of 0.6 wt% of colloidal particle, 0.07 wt% of hydrochloric acid, 30.5 wt% of isopropanol, and 68.83 wt% of water is preferably greater than 1.5 time, more preferably than 2.5 times, and even more preferably than 5 times of the number average diameter of colloidal particle in dispersion of 0.6 wt% of colloidal particle and 99.4 wt% of isopropanol.
• suitable colloidal particles include, for example, colloidal particles of metal salts, especially metal oxides.
• Suitable metal oxides include, for example, silica (Si0 2 ), titanium dioxide (Ti0 2 ), alumina ( ⁇ 1 2 ( 3 ⁇ 4), zirconium dioxide (Zr0 2 ), tin dioxide (Sn0 2 ), zinc oxide (ZnO), iron oxide (Fe 2 0 3 ) and mixtures thereof. More preferred are metal oxides with both partially hydrophobically modified and partially hydrophilically modified surfaces. Especially preferred, owing to their good compatibility with silanes, are both partially hydrophobically modified and partially hydrophilically modified silica particles.
• Illustrative silica-based particles suitable for use in this invention comprise at least 25% by weight silicon dioxide (i.e., silica), and preferably, at least 50% by weight silicon dioxide, and most preferably, at least 75%> to 100% by weight silicon dioxide, based on total weight of particle and including all ranges subsumed therein.
• silicon dioxide i.e., silica
• hydrophobically and hydrophilically modified silicas include those comprising at least one of the following groups:
• the silica-based particle used is pyrogenically produced silica (i.e. fumed silica) which has been both partially hydrophobically and partially hydrophilically modified.
• fumed silica pyrogenically produced silica
• the present inventors believe that the hierarchical structure of fumed silica contributes to the composition's ability to produce a hydrophobic coating.
• silicas comprising the group represented by formula (I), formula (II) or a combination thereof and -NH 2 .
• Such silicas are made, for example, commercially available from suppliers like Evonik Degussa GmbH under the names Aerosil ® R504 and NA 200 Y.
• the size of the colloidal particles used in this invention has no particular limitation save that the particles are necessarily colloidal. It is preferred, however that the particles have a primary particle size of less than 500 nm to avoid the final coating from being too opaque. More preferably the particle size is from 1 to 250 nm. Additionally or alternatively, the particles will have a primary particle size in the range of 0.1 to 100 nm, more preferably 1 to 50 nm and most preferably 3 to 13 nm.
• the composition preferably comprises the colloidal particles in an amount of from 0.001 to 8%, more preferably from 0.01 to 4%, even more preferably from 0.02 to 2% and most preferably from 0.05 to 1% by weight based on total weight of composition and including all ranges subsumed therein.
• the first hydrolyzed quatemary silane in this invention is a silane having at least two hydroxyl ligands. It is also possible that two or more silanol groups of the first hydrolyzed quatemary silane are condensed together to form oligomers. Silanol groups of the first hydrolyzed quatemary silane may additionally or alternatively be condensed with silanol groups of the second hydrolyzed quatemary silane to form mixed oligomers. However, this condensation should not lead to excessive polymerization, otherwise, the silanes may not be well dispersed and may even precipitate.
• the first hydrolyzed quatemary silane may have hydrophobic ligand(s) and/or hydrophilic ligand(s). However, it is preferred that the first hydrolyzed quatemary silane is a silane having at least two hydroxyl ligands and at least one hydrophobic ligand.
• the hydrophobic ligand(s) of the first hydrolyzed quatemary silane are preferably independently selected from alkyl, alkenyl, fluoroalkyl, fluoroalkenyl, aryl, fluoroaryl and combinations thereof.
• the first hydrolyzed quatemary silane may be hydrolyzed from a first quatemary silane precursor having the formula (R 1 2
• each R 1 is independently selected from alkoxy and halogen
• R is selected from alkyl, alkenyl, fluoroalkyl, fluoroalkenyl, aryl, fluoroaryl and combinations thereof;
• R is alkyl, especially C5-C20 alkyl.
• first quatemary silane precursor employed in this invention include those which comprise phenyltrimethoxysilane, phenyltriethoxysilane, phenyltrichlorosilane, benzyltrimethoxysilane, benzyltriethoxysilane, benzyltrichlorosilane, phenethyltrimethoxysilane, phenethyltriethoxysilane, phenethyltrichlorosilane, butyltrimethoxysilane, butyltriethoxysilane, butyltrichlorosilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, cyclohexyltrichlorosilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane, hexadecyltrichlorosi
• the first quatemary silane precursor is selected from pentyltnmethoxysilane, pentyltriethoxysilane, trichloropentylsilane, hexyltrimethoxysilane, hexyltriethoxysilane, trichlorohexylsilane, heptyltrimethoxysilane, heptyltriethoxysilane, trichloroheptylsilane, octyltrimethoxysilane, octyltriethoxysilane, trichlorooctylsilane, decyltrimethoxysilane, decyltriethoxysilane, trichlorodecylsilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, trichlorododecylsilane, hexa
• the first quatemary silane precursors suitable for use in this invention include hexyltrimethoxysilane, dodecyltrimethoxysilane, trichlorododecylsilane, and/or octadecyltriethoxysilane, all of which are commercially available from Tokyo Chemical Industry Co., Ltd (Japan).
• the composition preferably comprises the first hydrolyzed quatemary silane in an amount from 0.001 to 10%, more preferably from 0.05 to 5%, even more preferably from 0.1 to 2% and most preferably from 0.2 to 1% by weight based on total weight of composition and including all ranges subsumed therein.
• the composition additionally comprises solvent.
• Solvent as used herein especially refers to a liquid substance capable of dissolving a solute (a chemically different solid or liquid) to form a uniformly dispersed solution at the molecular or ionic size level. Liquid or solid refers to the state at 25°C and atmospheric pressure. Often solvent will make up the balance of the composition but optional ingredients such as colourants, preservatives and the like may also be present in the composition.
• the composition may comprise the solvent in an amount, for example, of from 50 to 99.9% by weight, more preferably from 70 to 99%, more preferably still from 80 to 98% by weight, and most preferably from 90 to 97% by weight.
• volatile solvents i.e. solvents which have a measurable vapour pressure at 25 °C. More preferred are solvents which have a vapour pressure at least equal to that of pure water at 25 °C Volatile solvents are preferred because of their tendency to evaporate quickly and so leave behind a coating consisting of (or at least consisting essentially of) silica-based particles, and first hydrolyzed silane.
• the silanes may polymerize during the drying process and undergo a so-called sol-gel transition. Without wishing to be bound by theory, the present inventors believe that polymerization of the silanes in the final coating composition may, in part, contribute to its excellent robustness.
• the solvent which has a refractive index close to that of the silanes.
• the solvent has a refractive index in the range 1.2 to 1.6, more preferably 1.3 to 1.5.
• Particularly preferred solvents are polar organic solvent, more preferably C 1 -C 4 alcohol.
• the solvent comprises methanol, ethanol, propanol, isopropanol or a mixture thereof.
• the solvent may additionally or alternatively comprise water, preferably in an amount of at least 5% by weight of the composition, more preferably at least 10%, more preferably still at least 20% and most preferably at least 30%.
• the amount of water in the composition may be up to 90% by weight of the composition. However, it is more preferred that water is present in the composition in amount of no greater than 80% by weight of the composition, even more preferably no greater than 70% for sake of easy formation of hydrophobic coating, coherency of the coating, and/or higher contact angle.
• the solvent comprises polar organic solvent (especially C 1 -C 4 alcohol) and water. More preferably the solvent comprises polar organic solvent and water in a weight ratio of polar organic solvent: water of from 50: 1 to 1 :20, even more preferably from 20:1 to 1:10, more preferably still from 10:1 to 1:5 and most preferably from 3:1 to 1:4.
• the composition may further comprise a second hydrolyzed quatemary silane.
• the present inventors have found that inclusion of the second hydrolyzed silane in compositions of the invention can provide coatings with excellent robustness, for example in terms of scratch and/or rub resistance.
• the second hydrolyzed quatemary silane in this invention is a silane with four hydroxyl ligands. It is also possible that two or more silanol groups of the second hydrolyzed quatemary silane are condensed together to form oligomers. However, this condensation should not lead to excessive polymerization, otherwise the silane may not be well dispersed and may even precipitate.
• the second hydrolyzed quatemary silane may be hydrolyzed from a second quatemary silane precursor having a formula (R 1 ) 4 Si.
• R 1 represents a ligand which can be hydrolyzed to a hydroxyl group.
• R 1 may, for example, be selected from alkoxy, halogen, or the like.
• Examples of the second quatemary silane precursor employed in this invention include those which comprise tetraethoxysilane (also called tetraethyl orthosilicate or TEOS), tetramethoxysilane (also called tetramethyl orthosilicate or TMOS), tetrapropoxysilane (also called tetrapropyl orthosilicate or TPOS), tetrabutoxysilane (also called tetrabutyl orthosilicate or TBOS), tetrabromosilane, tetrachlorosilane or a mixture thereof.
• the second quaternary silane precursor comprises TEOS, TBOS or a mixture thereof.
• the second quaternary silane precursors suitable for use in this invention include TEOS from Shanghai Chemical Reagent Co. Ltd (China) and/or TBOS from Sigma-Aldrich (Germany).
• the weight ratio of the first hydrolyzed silane to the second hydrolyzed silane in the composition may be at least 1:50, more preferably at least 1:30, more preferably still at least 1:20 and most preferably at least 1 : 10. To maximise hydrophobicity of the final coating, however, it is preferred that the weight ratio of the first hydrolyzed silane to the second hydrolyzed silane in the composition is no greater than 100:1, more preferably no greater than 20:1, more preferably still no greater than 5 : 1 and most preferably no greater than 1:1.
• the present inventors have also found that relatively low total amounts of silane are required to provide compositions which are both hydrophobic and robust. Moreover, excessive amounts of silane in the composition may lead to premature condensation polymerization and/or precipitation of the silanes.
• the composition may comprise the first hydrolyzed silane and the second hydrolyzed silane in a total amount of no more than 10% by weight of the composition, more preferably no more than 7%, more preferably still no more than 5%, even more preferably no more than 2%, even more preferably still no more than 1% and most preferably no more than 0.2%.
• the minimum amount of total silane (the amount of first hydrolyzed silane plus the amount of second hydrolyzed silane) is preferably at least 0.001% by weight of the composition, more preferably at least 0.005%, more preferably still at least 0.01 % and most preferably at least 0.02%.
• the composition comprises surfactant.
• the surfactant may be anionic, non-ionic, cationic, amphoteric, zwitterionic or a mixture thereof.
• cationic surfactants in particular may be employed in the composition of the invention without interfering with the ability of the composition to form a hydrophobic coating.
• the surfactant comprises cationic surfactant, more preferably at least 50% by total weight of surfactant in the composition is cationic surfactant, more preferably still at least 75% by weight, most preferably from 80 to 100%.
• Preferred cationic surfactants are quaternary ammonium salts. More preferably, the cationic surfactant has the formula JNTT ⁇ R ⁇ R 6 wherein R 3 , R 4 , R 5 and R 6 are independently (Ci to C 30 ) alkyl or benzyl. Preferably, one, two or three of R 3 , R 4 , R 5 and R 6 are independently (C 4 to C 30 ) alkyl and the other R 3 , R 4 , R 5 and R 6 group or groups are (Ci-Ce) alkyl or benzyl.
• the most preferred cationic surfactant is selected from cetyl-trimethylammonium bromide (CTAB), cetyl-trimethylammonium chloride (CTAC), behenyl-trimethylammonium chloride (BTAC), stearyl trimethyl ammonium chloride (STAC), benzyldimethyltetradecylammonium chloride (BDMTAC) and mixtures thereof.
• CTAB cetyl-trimethylammonium bromide
• CTAC cetyl-trimethylammonium chloride
• BTAC behenyl-trimethylammonium chloride
• STAC stearyl trimethyl ammonium chloride
• BDMTAC benzyldimethyltetradecylammonium chloride
• Anionic surfactant can often disrupt the ability of the composition to form a hydrophobic coating.
• surfactant when present is substantially free from anionic surfactant. More preferably less than 10% by total weight of surfactant in the composition is anionic surfactant, more preferably still less than 5% by weight, most preferably from 0 to 1% of the surfactant in the composition is anionic surfactant.
• the composition comprises surfactant in an amount of from 0.01 to 4% by weight.
• the composition comprises less than 1%> surfactant by weight of the composition, more preferably less than 0.7%>, even more preferably less than 0.5% and most preferably from 0.05 to 0.3%.
• the composition may be substantially free from surfactant. More preferably such compositions comprise less than 0.01% surfactant by weight of the composition, most preferably from 0 to 0.001%.
• the composition of the invention may have any suitable pH. However, it was surprisingly found that the stability of the compositions is best if they are slightly acidic. Thus it is preferred that the pH of the composition is in the range of 2 to 7, more preferably 3 to 5.
• the composition of the invention is used to prepare a hydrophobic coating.
• the method for making a hydrophobic coating on a surface preferably comprises the steps of applying the composition to a surface and allowing the composition to dry.
• the silanes may (further) polymerize during the drying process and undergo a so-called sol-gel transition. Without wishing to be bound by theory, the present inventors believe that polymerization of the silanes in the final coating composition may, in part, contribute to its excellent robustness.
• the coating will comprise less than 30% solvent by weight of the coating, more preferably less than 20%, more preferably still less than 10% and most preferably from 0.001 to 5%.
• the coating is hydrophobic.
• the coating may be ultrahydrophobic, or even superhydrophobic. More preferably, the coating may display a contact angle for water of at least 140 degrees or even from 150 to 160 degrees. Additionally or alternatively the coating may display a sliding angle for water of less than 15 degrees or even from 0.1 to 10 degrees.
• the coating is typically at least translucent and often transparent.
• the coating may display a transmittance value of at least 80%, more preferably at least 85% and most preferably from 87 to 95%.
• the composition of the present invention is preferably suitable for treating a hard surface, especially to aid cleaning or soil-resistance of the hard surface.
• Hard surface for the purposes of the present invention means any surface comprising a hard material such as glass, glazed ceramics, metal, stone, plastics, lacquer, wood, or combination thereof. Typically, the hard surface is in a household including window, kitchen, bathroom, toilet, furniture, floor, or the like.
• any general way for treating a hard surface is acceptable.
• the way for treating a hard surface by the composition is spraying the composition onto the hard surface, or wiping the hard surface by wipe impregnated with the composition, or pouring the composition onto the hard surface, or combination thereof.
• the way for treating a hard surface is spraying the composition onto a hard surface, and/or wiping a hard surface by wipe impregnated with the composition.
• spraying is employed for treating a hard surface, there is no limitation how the composition is sprayed.
• a spraying bottle for hard surface cleaning product is favourable.
• wipe including woven or nonwoven cloth, natural or synthetic sponges or spongy sheets, "squeegee” materials, paper towel, or the like is suitable.
• the wipe may be impregnated dry, or more preferably in wet form.
• composition exerts it effect by depositing hydrolyzed quaternary silane and/or its oligomer, and collodial particles onto a hard surface, forming a hydrophobic layer attached to the hard surface.
• the layer could enhance resistance to deposition of soil and/or stains or at least make such substances easier to remove.
• the method for treating a hard surface may optionally further comprises the steps of allowing soil and/or stains to deposit.
• the soil or stains will be easily removed when the hard surface is subsequently cleaned according to the method of this invention.
• the composition of the invention is also preferably applied to the hard surface during the subsequent cleaning.
• treating of a hard surface with the composition may be followed by a rinsing step, preferably with water.
• a most preferred method for treating a hard surface comprises:
• the present invention may also deliver other benefits such as long last cleaning, less effort for cleaning, less surface corrosion, less noise during cleaning, and/or scratch resistance. Further aspects of the present invention comprise methods for obtaining one or more these other benefits in a hard surface cleaning operation and/or use the composition in the methods in the manufacture of products for delivering any one more such benefits mentioned in this invention.
• the soils and stains of present invention may comprise all kinds of soils and stains generally encountered in the household, either of organic or inorganic origin, whether visible or invisible to the naked eye, including soiling solid debris and/or with bacteria or other pathogens. Specifically the method and compositions according to the invention maybe used to treat surface susceptible to fatty or greasy soil and stains.
• composition of the invention may be made in any convenient way.
• composition is prepared by a process comprising the steps of:
• step (iii) occurs prior to or during step (ii) as in this way the colloidal particles may to a greater or lesser extent interact with the silanes during the hydrolysis process. Especially where the particles comprise silica, this may lead to some bonding of hydrolyzed silane with the particles as we have found that durability of the final coating is improved if compositions are prepared in this manner (although with a slight loss of transparency).
• the process comprises the following steps:
• reaction mixture comprising both partially hydrophobically-modified and partially hydrophilically-modified colloidal particle, a first quatemary silane precursor, and water; and then
• step (iii) occurs prior to step (i) because in this case the colloidal particle may mix effectively in non-aqueous solvent and therefore this may lead to more robust coating.
• the process comprises the steps of:
• a) forming a pre-mixture comprising both partially hydrophobically-modified and partially hydrophilically-modified colloidal particle, first quatemary silane precursor, and nonaqueous solvent;
• second quatemary silane precursor may be hydrolyzed together with the first quatemary silane precursor to enhance the durability of the coating.
• the even more preferred process comprises the steps of:
• the mixture may comprise the first quatemary silane precursor and the second quatemary silane precursor in a total amount of no more than 10% by weight of the mixture, more preferably no more than 7%, more preferably still no more than 5%, even more preferably no more than 2% and most preferably no more than 1%.
• the minimum amount of total silane is preferably at least 0.001% by weight of the mixture, more preferably at least 0.005%, more preferably still at least 0.01% and most preferably at least 0.02%.
• the weight ratio of the first quatemary silane precursor to the second quatemary silane precursor in the composition may be at least 1 :50, more preferably at least 1 :30, more preferably still at least 1 :20 and most preferably at least 1:10. To maximise hydrophobicity of the final coating, however, it is preferred that the weight ratio of the first quaternary silane precursor to the second quaternary silane precursor in the composition is no greater than 100:1, more preferably no greater than 20:1, more preferably still no greater than 5 : 1 and most preferably no greater than 1:1. Hydrolysis of the quaternary silane precursors could be carried out when the mixture is either acidic or alkali. To avoid excessive polymerization, the mixture is preferably acidic.
• the pH value of the mixture is in the range of 2 to 7, most preferably 3 to 5.
• the acid used to tune the pH of the mixture for example, hydrochloric acid, sulphuric acid, citric acid, oxalic acid or combinations thereof may be used.
• the reaction mixture may additionally comprise polar organic solvent.
• the composition may be packed in any form, but preferably is packaged as a conventional hard surface treatment or cleaning product.
• the preferred packaging is a spray applicator. Pump dispersers (whether spray or non-spray pumps) and pouring applications (bottles etc) are also possible. It is also possible to impregnate a wipe with the composition.
• Silica-1 refers to Aerosil ® R504, hexamethyldisilazane and aminosilane-modified silica particles (average primary particle size 12 nm) supplied by Evonic AG.
• Silica-2 refers to Aerosil ® R812S, hexamethyldisilazane-modified silica particles (average primary particle size 7 nm) supplied by Evonic AG.
• Silica-3 refers to Aerosil ® A200, hydrophilic fumed silica (average primary particle size 12 nm) supplied by Evonic AG.
• HTMS was hexyltrimethoxysilane from Tokyo Chemical Industry Co., Ltd.
• TEOS was tetraethylorthosilicate from Sinopharm Chemical Reagent Co.
• dispersion I it was prepared by mixing the silica powders and isopropanol under sonication for 30 min. For other dispersion, the silica powders were blended with isopropanol under sonication for 30 min. Then, water was added into the mixture with sonication for 5 min. When used, hydrochloric acid (36.5%) was added along with water.
• the diameters were measured by Zetasizer NanoTM (Malvern Instruments Ltd, UK) for the aggregates with diameter no greater than ⁇ and the apparent volume median diameters were measured by Mastersizer 2000 (Malvern Instruments Ltd, UK) for the aggregates with diameter of greater than 1 um.
• the number average diameters of silicas in different dispersion are shown in Table 2.
• the diameter of the aggregates by the colloidal particle of the present invention (silica-1) is about 2.45 times of diameter in dispersion I.
• the hydrophobic colloidal particle without hydrophilic modification, silica-2 generated aggregates in dispersion ⁇ of 50.7 times of diameter of aggregates in dispersion I.
• dispersion ⁇ silica-1 aggregated around 2.36 times of that in dispersion I
• silica-2 aggregated 33 times of that in dispersion I. Since dispersion ⁇ and HI have more water than dispersion I, it is believed that the surface hydrophilicity of the colloidal particle of the present invention make it was better dispersed into dispersion with less water that the particle with only hydrophobic modification. When the colloidal particle was dispersed into dispersion with even less water, it was found that the colloidal particle of the present invention was easy to aggregate.
• dispersion IV the aggregates of colloidal particle of the present invention (silica-1) had about 5.15 times of diameter of aggregates in dispersion I.
• the hydrophilic particle, Silica-3 only aggregated about 1.8 times in dispersion IV of that in dispersion I. Due to the less content of water, the colloidal particle of the present invention was more difficult to be dispersed than the hydrophilic particle without any hydrophobic modification.
• the silicas were dispersed into isopropanol under stirring for 30 min at room temperature (25 °C). Then, the first quaternary silane precursor was added dropwise into the silica-silane mixture under stirring. If the composition comprises a second hydrolyzed silane, the second quaternary silane precursor was added dropwise along with the first quaternary silane precursor. After the addition of silane(s), the mixture was stirred for another 30 min. Hydrochloric acid (36.5 wt%) was diluted into water and then the diluted hydrochloric acid was added into the solution under stirring at room temperature for 3 hours to induce hydrolysis and condensation of the silane(s) and produce the compositions. Preparation of Coatings
• Pipette was used to drop the dispersions on the glass slide in a controlled amount. After the dispersion was dropped on the target surface, the tip of the pipette was used to spread the composition on the surface to ensure uniform coating.
• a trigger-sprayer which is widely used in home care or personal care products was used to apply the composition on surfaces. After the dispersion was sprayed towards the target surface, tissue or cloth was used to wipe the target surface in order to homogenize the coating and remove excess dispersion.
• the solvent was allowed to evaporate (typical evaporation time was 10-15 min) at room temperature. It is expected that the silanes undergo further polycondensation on the substrate surface to form a durable coating during this drying and, at the same time, the silica particles are embedded in the resulting network.
• DSA 100 Drop shape analysis system 100
• Kriiss was used to measure contact angle and sliding angle.
• DSA 100 with the tilting table maximum utilization of field of view up to 90 degrees was used for sliding angle test using deionised water drops of around 5 uL applied to five different points of each film and the sliding angle averaged over all 5 drops.
• the visible light transmittance of the coatings was measured by a UV-Vis spectrometer (Perkin- Elmer Lambda 650S).
• Durability of the coating was characterized by comparing the contact angle (CA) and sliding angle (SA) before and after abrasion test.
• the abrasion test was conducted by a modified automatic film applicator (Model 1133-N, Sheen). The glass slide with coating was placed underneath a ballerina cloth which glued with weight perpendicular to the coating. The automatic film applicator pushed the ballerina cloth move forward to brush the coated glass slide once at a speed of 100 mm/s. The pressure of the abrasion test was calculated to divide the mass by surface contact area.
• the contact angles and sliding angles were tested by following the method described above.
• composition of the present invention can produce hydrophobic coating, and the incorporation of the second quatemary silane into the composition is capable of improving the durability of the obtained coating.
• compositions were prepared by combining the ingredient in amount as listed in Table 3 by following the procedure of preparation of particle-silane composition. Then, the compositions were used to produce a coating on glass slides by following the procedure of preparation of coatings. Abrasion tests were conducted on each coating. The contact angles of the coatings were measured both before and after the abrasion. The number of each sample matches the number of the coatings made from that sample.
• compositions of the present invention were capable of yielding a coating with a contact angle over 150° as can be seen in Table 4. Even after abrasion, the coatings were still hydrophobic, indicating that the durability of the coating is excellent.
• the pressure of abrasion test is 3.2kPa.
• Coating 3 was generated by composition comprising the second hydrolyzed quaternary but not the first hydrolyzed quaternary silane. As shown in Table 4, a hydrophilic coating was generated. The incorporation of the first hydrolyzed quaternary silane is necessary to yield a hydrophobic coating.
• composition comprising colloidal particle which is both partially hydrophobic and partially hydrophilic can yield more hydrophobic coatings both before and after abrasion than other particles.
• compositions were prepared according to Table 5 and other experiments were similar with that in Example 1.
• the number of each sample matches the number of the coatings made from that sample.
• Table 6 shows the contact angles of coatings before and after the abrasion test by compositions comprising colloidal particles of the present invention, hydrophobic particles, and hydrophilic particles respectively. It was unexpectedly found that the contact angles were highest both before and after abrasion generated by the composition of the present invention among these three compositions.
• the colloidal particle which is partially hydrophobic and partially hydrophilic in composition with high amount of water was capable of yielding most hydrophobic coating both before and after abrasion among the three types of particles.
• This example demonstrates the composition comprising water in different amount yielded hydrophobic coatings.
• compositions were prepared according to Table 7 and other experiments were similar with that in Example 1.
• the number of each sample matches the number of the coatings made from that sample.
• the transmittances of coated glass slides were measured.
• the coherency of coating was also evaluated.
• the coated glass slide was completely immersed in a beaker filled with water for 5s. The slide was then removed vertically from the beaker, and any water remained on the back side of the glass slide was wiped away using paper towel.
• a rating (1-5) was given based on the amount of water residue observed by naked eyes on the side with coating. The more the water droplets remained, the lower the rating would be.
• 3 ⁇ 4e pressure of abrasion test is 2kPa.
• the transparency of each coating was very good.
• the coating was almost invisible on glass slides to naked eyes.
• coatings 6 were slightly better than other coatings in transparency.
• the coherency of coatings was also evaluated as shown in the last column of Table 8.
• the coherencies of coatings 3, 4 and 5 were extremely excellent without noticeable water droplet.
• the coherency of coatings 6 was slightly poorer than other three coatings, with a few water droplets, which may be caused by the high amount of water in the composition.

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