Coating compositions exhibiting corrosion resistance properties and related coated substrates

Abstract

Coating compositions are disclosed that include corrosion resisting particles such that the coating composition can exhibit corrosion resistance properties. Also disclosed are substrates at least partially coated with a coating deposited from such a composition and multi-component composite coatings, wherein at least one coating later is deposited from such a coating composition. Methods and apparatus for making ultrafine solid particles are also disclosed.

We claim: 
     
         1 . A coating composition comprising:
 (a) a thermosetting composition comprising a polyamine and an epoxy functional material; and   (b) magnesium oxide particles having a BET surface area of no more than 250 m 2 /g and a calculated equivalent spherical diameter (D (nm) ) of no more than 200 nanometers, wherein the calculated spherical diameter (D (nm) ) is determined according to the equation: D (nm) =6000/[BET (m 2 /g)*ρ(grams/cm)], wherein BET represents surface area as determined by nitrogen adsorption according to the ASTMD 3663-78 standard based on the Brunauer-Emmett-Teller method and p represents density,   wherein the magnesium oxide particles act as a corrosion resisting material.   
     
     
         2 . The coating composition of  claim 1 , wherein the polyamine comprises a polyamide resin. 
     
     
         3 . The coating composition of  claim 1 , wherein the thermosetting composition is formulated as a two-component composition where the polyamine is in one component and the epoxy functional material is in a second component. 
     
     
         4 . The coating composition of  claim 1 , wherein the thermosetting composition is capable of undergoing cure at ambient temperature. 
     
     
         5 . The coating composition of  claim 1 , wherein the composition is a solvent borne composition further comprising an organic solvent. 
     
     
         6 . The coating composition of  claim 1 , wherein the composition is formulated to be spray applied. 
     
     
         7 . The coating composition of  claim 1 , wherein the magnesium oxide particles have a calculated equivalent spherical diameter (D (nm) ) of from 100 to 200 nanometers. 
     
     
         8 . The coating composition of  claim 1 , wherein the magnesium oxide particles comprise at least 99% magnesium oxide. 
     
     
         9 . The coating composition of  claim 1 , wherein the magnesium oxide particles are not prepared from a gas phase synthesis. 
     
     
         10 . The coating composition of  claim 1 , wherein the magnesium oxide particles are prepared by hydrolysis. 
     
     
         11 . The coating composition of  claim 1 , wherein the magnesium oxide particles are cubic. 
     
     
         12 . The coating composition of  claim 1 , wherein the magnesium oxide particles are platy. 
     
     
         13 . The coating composition of  claim 1 , wherein the magnesium oxide particles are acicular. 
     
     
         14 . The coating composition of  claim 1 , wherein the magnesium oxide particles are present in the coating composition in an amount of 3 to 50 percent by volume, based on the total volume of the coating composition. 
     
     
         15 . The coating composition of  claim 1 , further comprising second corrosion resisting particles, other than the magnesium oxide particles. 
     
     
         16 . The coating composition of  claim 15 , wherein the magnesium oxide particles are present in the coating composition in an amount higher than any other inorganic particles acting as a corrosion resisting material. 
     
     
         17 . The coating composition of  claim 15 , wherein the second corrosion resisting particles comprise silicon, iron, calcium, lithium, potassium, manganese, zinc, aluminum, cerium, yttrium, molybdenum, tin, and/or titanium. 
     
     
         18 . The coating composition of  claim 15 , wherein the second corrosion resisting particles comprises an inorganic oxide. 
     
     
         19 . The coating composition of  claim 18 , wherein the inorganic oxide comprises titanium and/or lithium. 
     
     
         20 . The coating composition of  claim 15 , wherein the second corrosion resisting particles comprise non-chrome corrosion resisting particles. 
     
     
         21 . The coating composition of  claim 1 , wherein the corrosion resistance of a cured coating deposited from the coating composition is greater than that of a similar coating composition having the same epoxy functional material and polyamine but lacking the magnesium oxide particles. 
     
     
         22 . The coating composition of  claim 1 , wherein the coating composition is substantially chromate-free. 
     
     
         23 . A method of coating a substrate comprising:
 applying a first coating composition to at least a portion of the substrate, the first coating composition comprising a thermosetting composition comprising a polyamine, an epoxy functional material, and magnesium oxide particles having a BET surface area of no more than 250 m 2 /g and a calculated equivalent spherical diameter (D (nm) ) of no more than 200 nanometers, wherein the calculated spherical diameter (D (nm) ) is determined according to the equation: D (nm) =6000/[BET (m 2 /g)*ρ(grams/cm 3 )], wherein BET represents surface area as determined by nitrogen adsorption according to the ASTMD 3663-78 standard based on the Brunauer-Emmett-Teller method and p represents density,   wherein the magnesium oxide particles act as a corrosion resisting material.   
     
     
         24 . The method of  claim 23 , wherein the first coating composition is applied at a dry film thickness of 0.5 to 1.25 mils. 
     
     
         25 . The method of  claim 23 , wherein the substrate comprises an aluminum alloy. 
     
     
         26 . The method of  claim 23 , wherein the aluminum alloy is a 2024-T3 aluminum alloy. 
     
     
         27 . The method of  claim 23 , further comprising surface-treating the substrate prior to application of the first coating composition. 
     
     
         28 . The method of  claim 23 , further comprising applying a second coating composition onto the at least partially coated substrate. 
     
     
         29 . The method of  claim 28 , wherein the second coating composition comprises polyurethane. 
     
     
         30 . The method of  claim 23 , wherein the first coating composition is substantially chromate-free. 
     
     
         31 . A method for enhancing the corrosion resistance of a substrate comprising aluminum, the method comprising coating at least a portion of the substrate with the coating composition of  claim 1 . 
     
     
         32 . A coated substrate comprising:
 (a) an aluminum alloy; and   (b) a cured thermoset first coating on at least a portion of the surface of the aluminum alloy that is deposited from a first coating composition comprising a polyamine, an epoxy functional material, and magnesium oxide particles having a BET surface area of no more than 250 m 2 /g and a calculated equivalent spherical diameter (D (nm) ) of no more than 200 nanometers, wherein the calculated spherical diameter (D (nm) ) is determined according to the equation: D (nm) =6000/[BET (m 2 /g)*ρ(grams/cm 3 )], wherein BET represents surface area as determined by nitrogen adsorption according to the ASTMD 3663-78 standard based on the Brunauer-Emmett-Teller method and p represents density, wherein the magnesium oxide particles act as a corrosion resisting material.   
     
     
         33 . The coated substrate of  claim 32 , wherein the aluminum alloy comprises an aluminum cladding or further comprises a chromate conversion coating. 
     
     
         34 . The coated substrate of  claim 32 , wherein the first coating acts as primer coating, and the substrate has undergone pretreatment prior to being at least partially coated with the primer coating, and both the pretreatment and the primer coating are substantially free of chromium. 
     
     
         35 . The coated substrate of  claim 32 , further comprising a second coating deposited from a second coating composition applied to at least a portion of the primer coating, wherein the second coating composition is also substantially free of chromium. 
     
     
         36 . A coating system comprising:
 a) the coating composition of  claim 1 ; and   b) a second coating composition deposited over at least a portion thereof.   
     
     
         37 . The coating system of  claim 36 , wherein the second coating comprises a polyurethane coating.