FIELD

[0001] The present invention relates to coating compositions for coating a variety of substrates. In particular, the present invention relates to a hardcoat coating composition that provides an excellent properties as may be desired on metal and/or polymeric substrates.

BACKGROUND

[0002] Polymeric materials, particularly thermoplastics such as polycarbonate, are promising alternatives to glass for use as a structural material in a variety of applications, including automotive, transportation, and architectural glazing applications, where increased design freedom, weight savings, and improved safety features are in high demand. Plain polycarbonate substrates, however, are limited by their lack of abrasion, chemical, ultraviolet (UV), and weather resistance, and, therefore, need to be protected with optically transparent coatings that alleviate above limitations in the aforementioned applications. Metallic substrates, e.g., aluminum, may likewise need to be protected with coatings to provide abrasion resistance as well as corrosion resistance.

[0003] Silicone hard coats have been traditionally used to improve the abrasion resistance and UV resistance of various polymers including polycarbonate and acrylics. This enables the use of polycarbonates in a wide range of applications, including architectural glazing and automotive parts such as headlights. Such hard coats may also be used on metal substrates. Prior known silicone hard coats, however, tend to provide limited corrosion resistance, that may not be suitable to meet end user’s needs.

SUMMARY

[0004] Provided herein is a coating composition suitable for forming a silicone hardcoat. The silicone hardcoat composition includes, in one aspect, a silylated polyurethane additive. The inclusion of a silylated polyurethane additive has been found to provide excellent corrosion resistance when the hardcoat compositions are applied to a metal substrate. Additionally, the hardcoat composition provides excellent abrasion resistance, adhesion, and optical properties on a metal surface as well as when applied to polymeric substrates.

[0005] In one embodiment, the silicone hardcoat composition further includes a metal oxide or combination of metal oxide additives.

[0006] In one aspect provided is a hardcoat composition comprising: an organoalkoxysilane; a colloidal silica; a silylated polyurethane additive; a catalyst; and a solvent.

[0007] In one embodiment, the organoalkoxysilane is selected from a compound of the formula (R^aSi OR ² )^, wherein R ¹ is a Cl -CIO monovalent hydrocarbon, R ² is a Cl -CIO monovalent hydrocarbon or a hydrogen radical and a is 0, 1, or 2.

[0008] In one embodiment, R ¹ and R ² are selected from a C1-C10 alkyl.

[0009] In one embodiment in accordance with any of the previous embodiments, the organoalkoxysilane is selected from methyltrimethoxy silane.

[0010] In one embodiment in accordance with any of the previous embodiments, the silylated polyurethane is present in an amount of from about 1 wt.% to about 5 wt.% based on the weight of the composition.

[001 1] In one embodiment in accordance with any of the previous embodiments, the silylated polyurethane is present in an amount of from about 1.25 wt.% to about 4.5 wt.% based on the weight of the composition.

[0012] In one embodiment in accordance with any of the previous embodiments, the silylated polyurethane is present in an amount of from about 1.5 wt.% to about 4 wt.% based on the weight of the composition.

[0013] In one embodiment in accordance with any of the previous embodiments, the composition further comprises a metal oxide. In one embodiment, the metal oxide is selected from zirconia, titania, alumina, ceria, tin oxide, zinc oxide, antimony oxide, or a combination of two or more thereof. In one embodiment, the metal oxide is selected from zirconia or ceria. In one embodiment, the metal oxide is selected from zirconia and ceria. In one embodiment, the metal oxide is selected from zirconia and alumina. In one embodiment, the metal oxide is selected from alumina, zirconia, and ceria.

[0014] In one embodiment in accordance with any of the previous embodiments, the metal oxide is present in an amount of from about 0.5 wt.% to about 5 wt.% weight percent based on the weight of the composition.

[0015] In one embodiment in accordance with any of the previous embodiments, the hardcoat composition further compnses at least one additive selected from an antioxidant, a thermal stabilizer, an adhesion promoter, a afiller, a UV absorber, a light stabilizer, a corrosion inhibitor, a matting agent, a pigment, a flow modifier, a leveling agent, a surfactant or a combination of two or more thereof.

[0016] In one embodiment in accordance with any of the previous embodiments, the solvent is chosen from water, an aliphatic alcohol, a glycol ether, a cycloaliphatic alcohol, an aliphatic ester, a cycloaliphatic ester, an aliphatic hydrocarbon, a cycloaliphatic hydrocarbon, an aromatic hydrocarbon, a halogenated aliphatic compound, a halogenated cycloaliphatic compound, a halogenated aromatic compound, an aliphatic ether, a cycloaliphatic ether, an amide solvents, a sulfoxide solvent, or a combination of two or more thereof.

[0017] In one embodiment in accordance with any of the previous embodiments, the catalyst is at least one member selected from the group consisting of tetra-n-butyl ammonium acetate, tetra-n-butylammonium formate, tetra-n-butylammonium benzoate, tetra-n- butylammonium-2-ethylhexanoate, tetra-n-butylammonium-p-ethylbenzoate, tetra-n- butylammonium propionate and TBD-acetate ( acetate of l,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD)).

[0018] In another aspect, provided is a coating forming composition comprising the hardcoat composition in accordance with any of the previous embodiments, wherein the coating forming composition is applied to a substrate, said substrate selected from aluminum, an aluminum alloy, steel, galvanized steel, stainless steel, iron, copper, an acrylic polymer, a polyamide, a polyimide, an acrylonitrile-containing polymer, a polyvinyl halide, a polyolefin, a polycarbonate, or a copolycarbonate, a metal, a glass, or a combination of two or more thereof.

[0019] In still another aspect, provided is an article comprising a substrate and a coating, said coating formed from the hardcoat composition in accordancd with any of the previous embodiments, and covering at least a portion of said substrate.

[0020] In one embodiment, the substrate is chosen from aluminum, an aluminum alloy, steel, galvanized steel, stainless steel, iron, copper, an acrylic polymer, a polyamide, a polyimide, an acrylonitrile-styrene copolymer, a styrene-acrylonitrile-butadiene terpolymer, a polyvinyl halide, a polyethylene, a polycarbonate, a copolycarbonate, a metal, a glass, or a combination of two or more thereof.

[0021] In one embodiment, the coating composition is cured.

[0022] In one embodiment in accordance with any of the previous embodiments, the article comprises a primer coating disposed between the hardcoat coating and the substrate. [0023] In one embodiment in accordance with any of the previous embodiments, the substrate is aluminum and the coating was resistant to corrosion for at least 48 hours as evaluated by copper accelerated salt spray test method and more than 480 hrs from Neutral Salt Spray Resistance (NSS) Test- DIN EN ISO 9227.

[0024] In still another aspect, provided is a method of coating a substrate comprising applying the composition in accordance with any of the previous embodiments to a surface of a substrate. In one embodiment, the coating composition is applied by a coating deposition method selected from spray, dip, flow, spin.

[0025] These and other aspects and embodiments are further understood with respect to the detailed description.

DETAILED DESCRIPTION

[0026] Reference will now be made to exemplary embodiments, examples of which are illustrated in the accompanying drawings. It is to be understood that other embodiments may be utilized and structural and functional changes may be made. Moreover, features of the various embodiments may be combined or altered. As such, the following description is presented by way of illustration only and should not limit in any way the various alternatives and modifications that may be made to the illustrated embodiments. In this disclosure, numerous specific details provide a thorough understanding of the subject disclosure. It should be understood that aspects of this disclosure may be practiced with other embodiments not necessarily including all aspects described herein, etc.

[0027] As used herein, the words “example” and “exemplary” mean an instance, or illustration. The words “example” or “exemplary” do not indicate a key or preferred aspect or embodiment. The word “or” is intended to be inclusive rather than exclusive, unless context suggests otherwise. As an example, the phrase “A employs B or C,” includes any inclusive permutation (e g., A employs B; A employs C; or A employs both B and C). As another matter, the articles “a” and “an” are generally intended to mean “one or more” unless context suggest otherwise.

[0028] Provided is a coating composition that may form a coating with one or more desirable properties including, but not limited to, optical properties, adhesion, abrasion resistance, corrosion resistance, weatherability, and/or crack resistance. The composition is, in one embodiment, a silicon based hardcoat composition comprising a silylated polyurethane (SPUR) additive. The compositions optionally include a metal oxide additive, which may be in the form of a single metal oxide or a mixture of metal oxides. The compositions compnsing the silylated polyurethane additive have been found to exhibit excellent corrosion resistance on metal based substrates such as, for example, aluminum, as well as excellent scratch/abrasion resistance and adhesion. The composition can also be utilized as a coating on a polymeric substrate (e.g., polycarbonate and the like), and can provide excellent properties such as adhesion, abrasion resistance, optical clarity, and the like.

[0029] The silicon based hardcoat composition can be produced from a sol -gel coating solution. Sol-gel coatings are coatings produced by the sol-gel process. The sol-gel process is a process for synthesizing non-metallic, inorganic or hybrid polymeric materials from colloidal dispersions known as sols. In embodiments, the sol-gel coatings are produced by hydrolysis of aqueous dispersions of colloidal silicon dioxide and an organoalkoxysilane or mixtures of organoalkoxysilanes.

[0030] The organoalkoxysilane can be selected from a compound of the formula (R ¹ ) _a Si(OR ² )4 a, whereinRHs a Cl-ClO monovalent hydrocarbon radical, a C2-C8 monovalent hydrocarbon radical, or a C4-C6 monovalent hydrocarbon radical, and R ² is selected from a hydrogen radical or a Cl -CIO monovalent hydrocarbon radical, a C2-C8 monovalent hydrocarbon radical, or a C4-C6 monovalent hydrocarbon radical, and a is 0, 1 to 2. In one embodiment, R ¹ and R ² are independently selected from a Cl -CI O alkyl radical. Tn one embodiment, R ¹ and R ² are independently selected from methyl, ethyl, n-propyl, isopropyl, butyl, isobutyl, tertbutyl, pentyl, or hexyl. In one embodiment, R ¹ and R ² are independently selected from methyl and ethyl. In one embodiment, R ¹ and R ² are methyl. Examples of suitable organoalkoxysilanes include, but are not limited to, methyltrimethoxysilane, methyltriethoxysilane, or a mixture thereof, which can form a partial condensate. Additional organoalkoxysilanes include, but are not limited to, tetraethoxysilane, ethyltriethoxysilane, diethyldiethoxysilane, tetramethoxysilane, dimethyldimethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, etc.

[0031] It will be appreciated that the organoalkoxysilane may be provided by one type of silane, or a mixture of two or more different silanes.

[0032] The organoalkoxysilane may be present in an amount of from about 20 weight percent to about 40 weight percent, about 25 weight percent to about 50 weight percent, even from about 40 weight percent to about 75 weight percent, based on the total weight of the total silane composition. Here as elsewhere in the specification and claims, numerical values may be combined to form new and non-specified ranges.

[0033] The composition includes silica (SiCh) particles. The silica particles can be selected from a variety of different types of silica particles. In embodiments, the silica can be untreated, functionalized, surface charged, core shell/hollow silica particles, colloidal silica, acid or base stabilized silica, or a combination of two or more thereof.

L0034J In one embodiment, the composition includes colloidal silica. Generally, any colloidal silica can be used. The colloidal silica may be functionalized, acid stabilized, base stabilized, neutral/water-based, solvent based, and/or have a surface charge. The colloidal silica can, in embodiments, be core-shell particles or hollow particles. Particles of the same or different densities can be employed. Examples of suitable colloidal silica include, but are not limited to, fumed colloidal silica and precipitated colloidal silica. Particularly suitable colloidal silicas are those that are available in an aqueous medium. Such colloidal silica is referred to as a silica sol. Colloidal silicas in an aqueous medium are usually available in a stabilized form, such as those stabilized with sodium ion, ammonia, or an aluminum ion. The colloidal silica may have average particle diameters of from 5 to 250 nanometers, more specifically 10 to 150 nanometers, from 15 to 100 nanometers, even from 20 to 85 nanometers. Here as elsewhere in the specification and claims, numerical values may be combined to form new and non-specified ranges. Using relatively large colloidal silica particles has been found to provide a composition with excellent shelf life stability.

[0035] In one embodiment, the average particle diameters for the colloidal silica are determined in accordance with ASTM E2490-09 (2015), Standard Guide for Measurement of Particle Size Distribution of Nanomaterials in Suspension by Dynamic Light Scattering (DLS). [0036] Examples of suitable colloidal silica dispersions include, but are not limited to, those under the trademarks of LUDOX® AS-40 (Sigma Aldrich), Levasil®(Nouryon) SNOWTEX® (Nissan Chemical), BINDZIL® (Akzo Nobel) and NALCO® 1034A (Nalco Chemical Company), Idisil® (Evonik).

[0037] In one embodiment, the silica is a functionalized silica. It will be appreciated that functionalized colloidal silica can be employed. The silica can be functionalized with any group as may be suitable for a particular purpose or intended application. The silica can be fuctionalized with, for example, an epoxy group, an acrylate group, an alkenyl silane, .

[0038] The acrylate functionalized silica can be produced by adding an acrylate functional alkoxy silane to an aqueous silica colloid, heating the mixture to promote hydrolysis of the silane and condensation of silanol groups present on the silica nanoparticles with silanol groups or alkoxysilane groups of the acrylate functional silanes, and exchanging the aqueous phase with an organic phase by vacuum stripping. Examples of suitable acrylate functional alkoxy silanes include, but are not limited to, acryloxypropyl trimethoxysilane, methacryloxypropyl trimethoxysilane, acryloxypropyl triethoxysilane, or methacryloxypropyl triethoxysilane and mixtures thereof,

L0039J The alkenyl silane is not particularly limited, and exemplary alkenyl silanes include acryloxypropyl trialkoxysilanes and methacryloxypropyl trialkoxysilanes. Ethylenically unsaturated silanes such as vinyl trialkoxy silanes may also be used. For example, the alkenyl silane may comprise 3 -(trimethoxy silyl)propyl methacrylate.

[00401 In one embodiment, the silica is functionalized with a dispersing agent. Examples of suitable dispersing agents include, but are not limited to, a polyethyleneoxide alkoxysilane, a hydroxy carbonyl alkyl trialkoxysilane, a zwitterionic alkoxysilane, or an acrylic alkoxysilane. In select embodiments, the dispersing agent comprises a polyethyleneoxide silane, for instance a polyethylene glycol (PEG).

[0041] Hollow silica particles refers to silica particles having a cavity within an outer shell. The cavity may be substantially empty or may contain other materials such as hydrophobic organic compounds. The hollow silica particles may be dispersed in a dispersion medium (water or organic solvent) to form a colloid having a solid content of about 5% by weight (wt %) to about 40 wt %. Here, an organic solvent capable of being used as the dispersion medium may include: alcohols such as methanol, isopropyl alcohol (TP A), ethylene glycol, butanol, and the like; ketones such as methyl ethyl ketone, methyl isobutyl ketone (MIBK), and the like; aromatic hydrocarbons such as toluene, xylene, and the like; amides such as dimethyl formamide, dimethyl acetamide, N-methyl pyrrolidone, and the like; esters such as ethyl acetate, butyl acetate, y-butyrolactone, and the like; ethers such as tetrahydrofuran, 1,4-di oxane, and the like; and mixtures thereof. However, when a colloid solution in which the hollow silica particles are dispersed in a dispersion medium is used, as described above, it is desirable that the amount of the hollow silica be adjusted within the range as set forth above in consideration of solid content and the like.

[0042] The silica can be present in an amount of from about 5 weight percent to about 25 weight percent, from about 7 weight percent to about 20 weight percent, from about 10 weight percent to about 17 weight percent, or from about 12 weight percent to about 15 weight percent based on the weight of the composition. In one embodiment, the silica is present in an amount of from about 10 weight percent to about 20 weight percent based on the weight of the composition. In one embodiment, the silica is present in an amount of from about 15 weight percent to about 25 weight percent based on the weight of the composition.

[0043] Silylated Polyurethane [0044] The composition includes a silylated polyurethane (SPUR) additive. Silylated polyurethane compounds can be obtained by various methods including (i) reacting an isocyanate-termmated polyurethane (PUR) prepolymer with a suitable silane, e.g., one possessing both (a) a hydrolyzable functionality' at the silicon atom, such as, alkoxy etc., and (b) an active hydrogen-containing functionality such as mercaptan, primary' or secondary amine, etc., or (ii) reacting a hydroxyl-terminated PUR (polyurethane) prepolymer with a suitable isocyanate-tenninated silane, e.g., one possessing one to three alkoxy groups. Methods and reactions for preparing isocyanate-terminated and hydroxyl-terminated PUR prepolymers are described, for example, in U.S. Pat. Nos. 4,985,491; 5,919,888; 6,207,794; 6,303,731; 6,359,101; and 6,515,164 and published U.S. Patent Application Nos. 2004/0122253 and US 2005/0020706 (isocyanate-terminated PUR prepolymers); U.S. Pat. Nos. 3,786,081 and 4,481,367 (hydroxyl-terminated PUR prepolymers); U.S. Pat. Nos. 3,627,722; 3,632,557; 3,971,751; 5,623,044; 5,852,137; 6,197,912; and 6,310,170 (moisture-curable SPUR (silane modified/terminated polyurethane) obtained from reaction of isocyanate-terminated PUR prepolymer and reactive silane, e.g., aminoalkoxysilane); and, U.S. Pat. Nos. 4,345,053; 4,625,012; 6,833,423; and published U.S. Patent Application 2002/0198352 (moisture-curable SPUR obtained from reaction of hydroxyl-terminated PUR prepolymer and isocyanatosilane). The disclosures of the foregoing U.S. patents and published applications are incorporated by reference herein in their entirety. Other examples of moisture curable SPUR materials include those described in U.S. Pat. No. 7,569,653, the disclosure of which is incorporated by reference in its entirety.

[0045] A polyurethane prepolymer can be made by reacting a hydroxy-terminated polymeric material with an isocyanate to provide a prepolymer chain having NCO and/or OH groups at the ends thereof. The resulting polyurethane prepolymer is then reacted with a sufficient amount of a silane end-capper to provide a silylated polyurethane prepolymer.

[0046] The isocyanates that are reacted to form the polyurethane prepolymers can be organic isocyanates and include any of the known and conventional organic polyisocyanates, especially organic diisocyanates. Examples of suitable diisocyanates include, but are not limited to, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4' diphenylmethanediisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'- diisocyanate, various liquid diphenylmethane-diisocyantes containing a mixture of 2,4- and 4,4' isomers, Desmodur N® (Bayer) and the like, and mixtures thereof. Trimers can also bemployed. Examples of trimers include, but are not limited to, hexamethylene diisocyanate (so-called "HDI"), isophorone diisocyanate (so-called "IPDI"). Isophorone diisocyanate is especially advantageous for use in preparing the polyurethane prepolymers herein.

100471 The polyurethane prepolymer may be prepared by mixing the hydroxyterminated polymer and organic isocyanate together at ambient temperature and pressure, although the speed of the reaction is significantly increased if the temperature of the reaction mixture is raised to a higher temperature, for example, a temperature between 60-100° C. A molar ratio of NCO to OH from about 1.1 to about 4.0, depending on the selection of the particular hydroxyl-terminated polybutadiene polyol, is used to provide isocyanate-terminated polyurethane prepolymers. A molar ratio of NCO to OH from about 0.3 to about 0.95, and more preferably from about 0.5 to about 0.90, depending on the specific hydroxyl-terminated poly butadiene polyol, is used to provide hydroxyl group-terminated polyurethane prepolymers. [0048] Silylation of the isocyanate-terminated polyurethane prepolymer can be accomplished by reacting the prepolymer with a silane possessing at least one hydrolyzable group and at least one functionality which is reactive for isocyanate, such as, an active hydrogen-containing group such as hydroxyl, carboxylic acid, mercapto, and primary amino or secondary amino. In one embodiment, the silane is a primary or secondary aminosilane of the general formula:

[0049] R ³ -NH-R ⁴ -Si(R ⁵ ) _x -(OR ⁶ ) _3-x

[0050] wherein R ³ is hydrogen or an alkyl group of from 1 to 10 carbon atoms, R ⁴ is a divalent alkylene group of from 3 to 10 carbon atoms, R ⁵ and R ⁶ each independently is an alkyl group of from 1 to 6 carbon atoms or an aryl group of from 6 to 8 carbon atoms, and x has a value of 0, 1 or 2.

[0051] Examples of suitable aminosilanes include, but are not limited to, 3- aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 4-amino-3,3- dimethylbutyltrimethoxysilane, 4-amino-3,3-dimethylbutyldimethoxymethylsilane, N- methyl-3-amino-2 -methylpropyltrimethoxysilane, N-ethyl-3-amino-2- methylpropyltrimethoxysilane, N-ethyl-3-amino-2-methylpropyldiethoxymethylsilane, N- ethyl-3-amino-2-methylpropyltriethoxy silane, N-ethyl-3-amino-2- methylpropylmethyldimethoxysilane, N-butyl-3-amino-2-methylpropyltrimethoxysilane, 3 (N-methyl-2-amino-l -methyl-1 -ethoxy )-propyltrimethoxysilane, N-ethyl-4-amino-3,3- dimethylbutyldimethoxymethylsilane and N-ethyl-4-amino-3,3- dimethylbutyltrimethoxysilane trimethoxysilane, and the like. [0052] In one embodiment, the polyurethane prepolymers can be substantially fully silylated, i.e., all, or substantially all, of the isocyanate groups can be reacted with silane to provide a completely silylated polyurethane polymer.

[0053] Silylation of a hydroxyl-terminated polyurethane prepolymer can be accomplished by reacting the prepolymer with an isocyanatosilane. Suitable isocyanatosilanes are those of the general formula:

[0054] OCN-R ⁷ -Si(R ⁸ ) _y -(OR ⁹ ) _3-y

[0055] wherein R ⁷ is a divalent alkylene group of from 3 to 10 carbon atoms, R ⁸ and R ⁹ each independently is an alkyl group of from 1 to 6 carbon atoms or an aryl group of from 6 to 8 carbon atoms, and y has a value of 0, 1 or 2.

[0056] Examples of such isocyanatosilanes for use in the silylation procedure are X- isocyanatopropyltnmethoxysilane, /.-isocyanatopropyltnethoxy-silane. X- isocyanatomethylpropyltrimethoxysilane, X-isocyanatomethylpropyltri ethoxysilane, X- isocyanatopropylmethyldimethoxysilane, X-isocyanatopropyldimethylmethoxysilane and X- isocyanatomethylpropyldimethylmethoxysilane, and the like.

[0057] In one embodiment, the silylation of the hydroxyl-terminated polyurethane prepolymers herein will be substantially complete, i.e., substantially no hydroxyl groups will be present following silylation, where the silylated polymers are to be incorporated in such products as sealants and coatings.

[0058] The silylated polyurethane is present in the composition in an amount of from about 1 wt.% to about 5 wt.%, from about 1.25 wt.% to about 4.5 wt.%, from about 1.5 wt.% to about 4 wt.%, or from about 2 to about 3 wt.% based on the total weight of the composition. [0059] The composition optionally includes metal oxide particles. The metal oxide particles used in the composition of the invention are not particularly limited. Generally, the metal particles will be metal oxide particles. In one embodiment, the metal is selected from a transition metal. The metal oxide particles can be oxides of metals such as, but not limited to, zirconium, titanium, aluminum, cerium, zinc, copper, iron, magnesium, nickel, copper, etc. Suitable examples include, but are not limited to, zirconia, titania, alumina, ceria, zinc oxide, or a combination of two or more thereof. In one embodiment, the composition includes a mixture of zirconia and ceria. In one embodiment, the composition includes a mixture of zirconia and alumina. In one embodiment, the composition includes a mixture of alumina, zirconia, and ceria.

[0060] The metal oxides can be functionalized. The functional groups can be selected as desired for a particular purpose or intended application. The metal oxides can be provided as part of a dispersion where the metal oxides are dispersed in a medium. The dispersion medium is not particularly limited and can be selected as desired. The dispersion medium can be water based or solvent based.

[0061] The size of the metal oxide particles may be selected as desired for a particular purpose or intended application. In embodiments, the metal oxide particles are nano sized particles. Nanoparticles may have dimensions in the range of one to about 500 nanometers. For clear coat applications, the particles should have a size below a certain limit such that it will not scatter light passing through the coating. Particles with dimensions less than X/2 do not scatter light of X, where X is the wavelength of light, and will not disrupt the transparency of the matrix in which they are incorporated. In embodiments, the metal particles have a diameter of 190 nanometers or less. In other embodiments, the metal particles have an average diameter of from about 1 nm to about 190 nm; from about 5 nm to about 175 nm; from greater than 15 nm to about 150 nm; or from about 20 nm to about 100 nm. Here as elsewhere in the specification and claims, numerical values may be combined to form new and non-specified ranges.

[0062] In one embodiment, the particle diameters for the metal oxide particles are determined in accordance with ASTM E2490-09 (2015), Standard Guide for Measurement of Particle Size Distribution of Nanomaterials in Suspension by Dynamic Light Scattering (DLS). [0063] When a plurality of metal oxides is employed the metal oxides can be provided with different sizes, morphologies, functionalities, etc. In one embodiment, the composition employs a first metal oxide having a first particle size, and a second metal oxide having a secod particle size. The first and second metal oxides can be the same or different from one another in terms of the type of metal.

[0064] The metal oxide(s), when employed, can be present in an amount of from about 0.5 wt.% to about 5 wt.%, from about 0.75 wt.% to about 4 wt.%, from about 1 wt.% to about 3 wt.%, or from about 1.5 to about 2.5 wt.% based on the total weight of the composition./ [0065] Examples of suitable metal oxides include, but are not limited to, those available from Nyacol such as, for example, Nyacol® AL27 (Nyacol), Nyacol® AL20 (Nyacol), Nyacol® AL20DW (Nyacol) Nyacol® Colloidal Zirconia ZrO2(OAC) acetate stabilized (Nyacol), Zr50/14 pH 3, Zr 100/20 etc. (Nyacol), Alumina dispersions in isopropanol & water (Sigma Aldrich).

[0066] The composition also comprises a solvent. The solvent is not particularly limited. In one embodiment, the solvent may be chosen from water, an aliphatic alcohol, a glycol ether, a cycloaliphatic alcohol, an aliphatic ester, a cycloaliphatic ester, an aliphatic hydrocarbon, a cycloaliphatic hydrocarbon, an aromatic hydrocarbon, a halogenated aliphatic compound, a halogenated cycloaliphatic compound, a halogenated aromatic compound, an aliphatic ether, a cycloaliphatic ether, an amide solvents, a sulfoxide solvent, or a combination of two or more thereof. Examples of suitable solvents include, but are not limited to, alcohols, such as methanol, ethanol, propanol, isopropanol, n-butanol, tert-butanol, methoxypropanol, ethylene glycol, diethylene glycol butyl ether, or combinations thereof. Other polar organic solvents such as acetone, methyl ethyl ketone, ethylene glycol monopropyl ether, and 2-butoxy ethanol, can also be utilized. In embodiments, the solvent used is one or more selected from 1- methoxy-2-propanol, diacetone alcohol (DAA), acetyl acetone, cyclohexanone, methoxy propylacetate, ketones, glycol ether, or mixtures of two or more thereof. The amount of solvent in the composition ranges preferably from about 25 wt.% to about 85 wt.%, more preferably from about 40 wt.% to about 80 wt.%, and most preferably from about 50 wt.% to about 75 wt.%, all based on the total weight of the composition.

[0067] The composition may also comprise a catalyst. The catalyst is not particularly limited and any suitable catalyst for curing the coating composition can be used. In one embodiment, the catalyst is at least one member selected from the group consisting of tetra-n- butylammonium acetate, tetra-n -butyl ammonium formate, tetra-n-butyl ammonium benzoate, tetra-n-butylammonium-2-ethylhexanoate, tetra-n-butylammonium-p-ethylbenzoate, tetra-n- butylammonium propionate and TBD-acetate (acetate salt of l,5,7-triazabicyclo[4.4.0]dec-5- ene (TBD)).

[0068] An acid catalyst can be employed for pre-condensation portions of the reaction. Suitable acid catalysts include, but are not Imited to, mineral acids, carboxylic acids, and sulfonic acids such as alkanesulfonic acids and arylsulfonic acids. Exemplary acid catalysts include, but are not limited to: hydrofluoric acid, hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, perchloric acid, phosphoric acid, acetic acid, propionic acid, butanoic acid, oxalic acid, malonic acid, trifluoroacetic acid, trichloroacetic acid, methanesulfonic acid, trifluoromethanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, and phenolsulfonic acid, and preferably acetic acid, butanoic acid, toluenesulfonic acid, trifluoromethanesulfonic acid, and hydrochloric acid.

[0069] The catalyst can be added to the coating formulation as desired for a particular purpose or intended application. Generally, the catalyst should be added in an amount that will not affect or impair the physical properties of the coating, but in a sufficient amount effective to catalyze the curing reaction. In one embodiment, the catalyst is provided in an amount ranging from 1 ppm to about 75 ppm; from about 10 ppm to about 70 ppm; even from about 20 ppm to about 60 ppm. Here, as elsewhere in the specification and claims, numerical values may be combined to form new and non-specified ranges. The “ppm” value of the catalyst may be defined as parts per million.

[0070] The coating compositions may include other materials or additives to provide the coating with desired properties for a particular purpose or intended application. For example, the composition may also include other additives such as hindered amine light stabilizers, antioxidants, corrosion inhibitors, UV absorbers, matting agents, pigments, flow modifiers, leveling agents, or a combination of two or more thereof. In one emodient, a composition for coating a metal may also include one or more matting agents to produce a matte effect. In one embodiment, the matting agent can be silica based . Examples of suitable matting agents include, but are not limited to, SYLOID®, LUBRIZOL®, PERGOPAK®. Corrosion inhibitors can also be employed. The corrosion inhibitor can be organic or inorganic. Examples of inhibitors include, but are not limited to, chromate, nitrite, nitrate, phosphate, tungstate, and molybdate, or organic inhibitors include sodium benzoate or ethanolamine. Examples of suitable inhibitors include HALOX®,Benztriazole, 8 hydroxy quinoline, and the like.

[0071] The UV absorbers can also be chosen from a combination of inorganic UV absorbers and organic UV absorbers. Examples of suitable organic UV absorbers include but are not limited to, those capable of co-condensing with silanes. Such UV absorbers are disclosed in U.S. Patent Nos. 4,863,520, 4,374,674, 4,680,232, and 5,391,795 which are herein incorporated by reference in their entireties. Specific examples include 4-[gamma- (trimethoxysilyl) propoxyl]-2-hydroxy benzophenone and 4-[gamma-(tri ethoxysilyl) propoxyl] -2 -hydroxy benzophenone and 4,6-dibenzoyl-2-(3-triethoxysilylpropyl) resorcinol. When the UV absorbers that are capable of co-condensing with silanes are used, the UV absorber should co-condense with other reacting species by thoroughly mixing the coating composition before applying it to a substrate. Co-condensing the UV absorber prevents coating performance loss caused by the leaching of free UV absorbers to the environment during weathering.

[0072] The catalyst can be added to the coating composition directly or can be dissolved in a solvent or other suitable carrier. The solvent may be a polar solvent such as methanol, ethanol, n-butanol, t-butanol, n-octanol, n-decanol, l-methoxy-2-propanol, isopropyl alcohol, ethylene glycol, tetrahydrofuran, dioxane, bis(2 -methoxy ethyl)ether, 1,2- dimethoxyethane, acetonitrile, benzonitrile, methylethyl ketone, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), JV-methylpyrrolidinone (NMP), and propylene carbonate. Adding solvents such as, for example, alcoholic solvents is employed to stop or slow down the hydrolysis of the sol-gel solution.

|0073J The composition of the invention can also include surfactants as leveling agents.

Examples of suitable surfactants include, but are not limited to, surfactants such as silicone polyethers under the designation Silwet® and CoatOSil® available from Momentive Performance Materials, Inc. of Albany, N.Y., FLUORAD™ from 3M Company of St. Paul, Minn., and polyether-polysiloxane copolymers such as BYK® -302 manufactured by BYK®- Chemie. Suitable antioxidants include, but are not limited to, hindered phenols (e.g. IRGANOX® 1010 from Ciba Specialty Chemicals).

[0074] In one embodiment, the composition is a non-epoxy coating. Non-epoxy coatings may be particularly suitable for use with metallic substrates such as, for example, aluminum substrates.

[0075] In another embodiment, the composition optionally includes an epoxy silane. An example of suitable epoxy-terminated silane compounds include epoxy-terminated alkoxy silanes of the structure:

[0076] G-L-Si(R ¹⁰ ) _m — (OR ⁿ )3- _m

[0077] wherein:

[0078] L is a divalent linkage,

[0079] R ¹⁰ and R ¹¹ are independently selected from C1-C4 alkyl groups,

[0080] G is a glycidoxy or epoxy cyclohexyl group, and

[0081] m is O or l.

[0082] In one embodiment, L is selected from an alkylene, an alkylene ether, both either linear or branched, or a bond. In one embodiment, the divalent linkage L is — CH2CH2CH2O — or — CH2CH2— .

[0083] Examples of suitable epoxy-functional alkoxysilanes include, but are not limited to, glycidoxymethyl-trimethoxysilane, glycidoxymethyltriethoxysilane, glycidoxymethyl-tripropoxysilane, glycidoxymethyl-tributoxysilane, [>- glycidoxy ethyltrimethoxysilane, P-glycidoxyethyltriethoxysilane, P-glycidoxyethyl- tripropoxysilane, P-glycidoxyethyl-tributoxysilane, P-glycidoxyethyltrimethoxysilane, a- glycidoxyethyl-tri ethoxysilane, a-glycidoxyethyl -tripropoxysilane, a- glycidoxy ethyltributoxysilane, y-glycidoxypropyl-trimethoxysilane, y-glycidoxypropyl- triethoxysilane, y-glycidoxypropyl-tripropoxysilane, y-glycidoxypropyltributoxysilane, P- glycidoxypropyl-trimethoxysilane, P-glycidoxypropyl-tri ethoxysilane, P-glycidoxypropyl- tnpropoxysilane, P-glycidoxypropyltnbutoxysilane, a-glycidoxypropyl-trimethoxysilane, a- glycidoxypropyl-tri ethoxysilane, a-glycidoxypropyl-tripropoxysilane, a- glycidoxypropyltributoxysilane, y-glycidoxybutyl-trimethoxysilane, 6-glycidoxybutyl- tnethoxysilane, 6-glycidoxybutyl-tnpropoxysilane, 6-glycidoxybutyl-tnbutoxysilane, 6- glycidoxybutyl-trimethoxysilane, y-glycidoxybutyl -triethoxysilane, y-glycidoxybutyl- tripropoxysilane, y-propoxybutyl-tributoxysilane, 5-glycidoxybutyl-trimethoxysilane, 8- glycidoxybutyl-triethoxysilane, 6-glycidoxybutyl-tripropoxysilane, a-glycidoxybutyl- trimethoxysilane, a-glycidoxybutyl-triethoxysilane, a-glycidoxybutyl-tripropoxysilane, a- glycidoxybutyl-tributoxysilane, (3,4-epoxycyclohexyl)-methyl-trimethoxysilane, (3,4- epoxycyclohexyl)methyl-triethoxysilane, (3,4-epoxycyclohexyl)methyl-tripropoxysilane, (3,4-epoxycyclohexyl)-methyl-tributoxysilane, (3,4-epoxycyclohexyl)ethyl-trimethoxysilane, (3,4-epoxycyclohexyl)ethyl-triethoxysilane, (3,4-epoxycyclohexyl)ethyl-tripropoxysilane, (3,4-epoxycyclohexyl)-ethyl-tributoxysilane, (3,4-epoxycyclohexyl)propyl-trimethoxysilane, (3,4-epoxycyclohexyl)propyl-triethoxysilane, (3,4-epoxycyclohexyl)propyl-tripropoxysilane, (3,4-epoxycyclohexyl)propyl-tributoxysilane, (3,4-epoxycyclohexyl)butyl-trimethoxysilane, (3,4-epoxycyclohexyl)butyl-triethoxysilane, (3,4-epoxycyclohexyl)-butyl-tripropoxysilane, and (3,4-epoxycyclohexyl)butyl-tributoxysilane.

[0084] If an epoxy silane is employed in the composition, the epoxy silane can be present in an amount of from about 0.5 wt.% to about 50 wt.%, from about 1 wt.% to about 40 wt.%, from about 5 wt.% to about 30 wt.%, or from about 10 wt.% to about 20 wt.% based on the total weight of the composition. In one embodiment, the epoxy silane is present in an amount of from about 20 wt.% to about 50 wt.%.

[0085] The compositions can be prepared by any suitable method. In one embodiment, the compositions are prepared by mixing the alkoxysilane, silylated polyurethane and an acid together. To this mixture, the silica sol is added. Alcohol solvents, a catalyst, and optional flow additives are added following addition of the silica. The composition is mixed sufficiently and can be aged for several days and, in embodiments, is aged for 5 days.

[0086] In another embodiment, the composition can be prepared by mixing the alkoxysilane, silica, and optional epoxy silane. To this mixture, the silylated polyurethane and optionally the metal oxide(s) is added with stirring. The catalyst and optional flow additive is added and the composition is mixed and aged as appropriate.

[0087] The compositions described herein may be employed as a coating for a substrate of interest. The coating may be cured to form a hardcoat top coat. The coating may be applied to a portion of a surface of the substrate or the entire surface of a substrate to be coated. Examples of suitable substrates include, but are not limited to, metal materials and organic polymeric materials.

L0088J Examples of suitable metal materials that may be coated with the present compositions include, but are not limited to, aluminum, aluminum alloys (such as, but not limited to, 2K, 3K, 5K, 6K, both bare and anodized) steel, galvanized steel, stainless steel, iron, copper, and the like.

[00891 Examples of suitable polymeric materials that can be coated with the present compositions include, but are not limited to, acrylic polymers, e.g., poly(methylmethacrylate), polyamides, polyimides, acrylonitrile-styrene copolymer, styrene-acrylonitrile-butadiene terpolymers, polyvinyl chloride, polyethylene, polycarbonates, copolycarbonates, high-heat polycarbonates, metal, glass, a combination of two or more thereof, and any other suitable material. The polymeric materials can comprise a blend of polymeric materials. The polymeric material, or surface comprising the polymeric material, can be untreated or treated as may be desired for a particular application. Surface treatments of the polymeric material may include, but are not limited to, plasma treatment, ozone treatment, and the like. The polymeric material can be provided in any shape as desired for a particular purpose or end application. The polymeric material can provide a substantially flat surface or it can be contoured in any three- dimensional shape having a uniform or non-uniform surface topography.

[0090] The coating composition provides excellent properties to the substrate to which it is applied. They exhibit excellent adhesion on metal and polymeric substrates. They also provide excellent abrasion or scratch resistance. With respect to metal substrates, the coating composition offer enhanced corrosion protection relative to known silicon based hardcoat compositions. In embodiments, the compositions can provide corrosion resistance as evaluated by copper accelerated salt spray (CASS) methods of greater than 48 hours and Neutral Salt Spray Resistance (NSS) Test of greater than 480 hrs, whereas many conventional silicon based hard coats have corrosion resistance performance of 8 hours or less

[0091] The coating composition can be applied to a substrate with or without the aid of a primer material. The primer material may be chosen from any material suitable for facilitating adhesion of the topcoat material to the substrate. The primer material is not particularly limited, and may be chosen from any suitable primer material. In one embodiment, the primer is chosen from homo and copolymers of alkyl acrylates, polyurethanes, polycarbonates, polyvinylpyrrolidone, polyvinylbutyrals, poly(ethylene terephthalate), polyibutylene terephthalate), or a combination of two or more thereof. In one embodiment, the primer may be polymethylmethacrylate. [0092] In one embodiment, a primer layer is applied to the substrate prior to applying the coating composition. The primer may be coated onto a substrate by flow coat, dip coat, spin coat, spray coat, or any other methods known to a person skilled in the field, it is optionally allowed to dry by removal of any solvents, for example by evaporation, thereby leaving a dry coating. The primer may subsequently be cured. It will be appreciated that the primer does not have to be dried priorto application of a topcoat Additionally, atopcoat (e.g., ahardcoat layer) may be applied on top of the primer layer by flow coat, dip coat, spin coat or any other methods known to a person skilled in the field. Optionally, a topcoat layer may be directly applied to the substrate without a primer layer.

[0093] The following examples illustrate embodiments of materials in accordance with the disclosed technology. The examples are intended to illustrate embodiments of the disclosed technology, and are not intended to limit the claims or disclosure to such specific embodiments. [0094] EXAMPLES

[0095] Adhesion testing is conducted using ASTM D 3359. Copper Accelerated Salt Spray Resistance (CASS) Test - DIN EN ISO 9227 and Neutral Salt Spray Resistance (NSS) Test- DIN EN ISO 9227 are utilized to evaluate corrosion resistance.

[0096] SPUR, methyltrimethoxy silane (MTMS), and acetic acid (AcOEI) were added to a suitable container and stirred for 30 minutes to dissolve the SPUR. The mixture was cooled to <10 °C. In another container, colloidal silica (LUDOX®) was taken and diluted with water. It was then added to the first mixture of MTMS and SPUR solution while maintaining the internal temperature <15 °C. After the addition was complete, it was diluted with isopropyl alcohol (IP A) and n-butyl alcohol (nBuOH) and stirred at room temperature for 16 hours. That composition was then charged with BYK302, tetrabutyl ammonium acetate (TBAA), AcOH, solvents, SDBR (30% solution, only for PC) and Manchem FPM (for compositions to be used on metal) successively at room temperature. The resultant formulation was stirred at room temperature for an additional 2 hours and kept inside a 50 °C oven for 5 days. After aging for 5 days, it was filtered through filter pad and used for coating. [0097] Exemplary compositions are illustrated in Tables 1 and 2.

Table 2

[0098] The compositions employed in Table 1 are coated on metal substrates. The compositions in Table 2 are coated on polycarbonate substrates. CE-1 and CE-2 are compositions that do not include any silylated polyurethane. As shown in Tables 1 and 2 the coating compositions in accordance with aspects of the present invention that utilize a silylated polyurethane exhibit good adhesion to metal and polymeric surfaces as well as providing excellent corrosion resistance and scratch resistance. Table 1

[0099] While the above description contains many specifics, these specifics should not be construed as limitations on the scope of the invention, but merely as exemplifications of preferred embodiments thereof. Those skilled in the art may envision many other possible variations that are within the scope and spirit of the invention as defined by the claims appended hereto.