Coatable composition, antistatic composition, antistatic articles, and methods of making the same

Abstract

A method of making a coatable composition includes: providing a first composition comprising silica nanoparticles dispersed in an aqueous liquid vehicle, wherein the first composition has a pH greater than 6; acidifying the first composition to a pH of less than or equal to 4 using inorganic acid to provide a second composition; and dissolving at least one metal compound in the second composition to form the coatable composition. The silica nanoparticles have a polymodal particle size distribution, wherein the polymodal particle size distribution comprises a first mode having a first particle size in the range of from 8 to 35 nanometers, wherein the polymodal particle size distribution comprises a second mode having a second particle size in the range of from 2 to 20 nanometers, wherein the first particle size is greater than the second particle size. Coatable compositions, antistatic compositions, preparable by the method are also disclosed. Soil-resistant articles including the antistatic compositions are also disclosed.

What is claimed is: 
     
         1 . A method of making an antistatic article, the method comprising the steps:
 a) providing a first composition comprising silica nanoparticles dispersed in an aqueous liquid medium, wherein the silica nanoparticles have a polymodal particle size distribution, wherein the polymodal particle size distribution comprises a first mode having a first particle size in the range of from 8 to 35 nanometers, wherein the polymodal particle size distribution comprises a second mode having a second particle size in the range of from 2 to 20 nanometers, wherein the first particle size is greater than the second particle size, and wherein the first composition has a pH greater than 6;   b) acidifying the first composition to a pH of less than or equal to 4 using inorganic acid to provide a coatable composition; and   d) coating a layer of the coatable composition onto a surface of a substrate; and   e) at least partially drying the layer of the coatable composition to provide an antistatic layer, wherein the antistatic layer has an average surface conductivity of less than or equal to 10 9  ohms per square at 25° C. and 50 percent relative humidity.   
     
     
         2 . The method of  claim 1 , further comprising dissolving at least one metal compound in the coatable composition. 
     
     
         3 . The method of  claim 2 , wherein said at least one metal compound is selected from the group consisting of manganese compounds, silver compounds, vanadium compounds, tin compounds, platinum compounds, and combinations thereof. 
     
     
         4 . The method of  claim 2 , wherein said at least one metal compound is selected from the group consisting of silver compounds, vanadium compounds, and combinations thereof. 
     
     
         5 . The method of  claim 1 , wherein the substrate comprises at least one of glass or an organic polymer. 
     
     
         6 . The method of  claim 5 , wherein the organic polymer comprises polyethylene terephthalate. 
     
     
         7 . The method of  claim 1 , wherein the antistatic layer is optically clear. 
     
     
         8 . The method of  claim 1 , wherein the antistatic layer has a thickness in a range of from 0.02 to 100 microns. 
     
     
         9 . The method of  claim 1 , wherein the inorganic acid has a pK a  of less than or equal to zero. 
     
     
         10 . The method of  claim 1 , wherein step b) comprises acidifying the first composition to a pH of less than or equal to 2. 
     
     
         11 . The method of  claim 1 , wherein the coatable composition is essentially free of organic non-volatile compounds. 
     
     
         12 . An antistatic article made according to the method of  claim 1 . 
     
     
         13 . An antistatic composition comprising an amorphous silica matrix, wherein the amorphous silica matrix comprises interconnected silica nanoparticles, wherein the silica nanoparticles have a polymodal particle size distribution, wherein the polymodal particle size distribution comprises a first mode having a first particle size in the range of from 8 to 35 nanometers, wherein the polymodal particle size distribution comprises a second mode having a second particle size in the range of from 2 to 20 nanometers, wherein the first particle size is greater than the second particle size. 
     
     
         14 . The antistatic composition of  claim 13 , further comprising metal cations, wherein a majority of the metal cations are individually disposed in the amorphous silica matrix, and wherein the metal cations comprise from 0.5 to 20 mole percent of the total combined moles of silicon and metal cations in the composition. 
     
     
         15 . The antistatic composition of  claim 14 , wherein the metal cations are selected from the group consisting of manganese cations, silver cations, vanadium cations, tin cations, platinum cations, and combinations thereof. 
     
     
         16 . The antistatic composition of  claim 14 , wherein the metal cations are selected from the group consisting of silver cations, vanadium cations, and combinations thereof. 
     
     
         17 . The antistatic composition of  claim 13 , wherein the antistatic composition is essentially free of organic non-volatile compounds. 
     
     
         18 . An antistatic article comprising a layer of an amorphous antistatic composition disposed on a surface of a substrate, wherein the amorphous silica matrix comprises interconnected silica nanoparticles, wherein the silica nanoparticles have a polymodal particle size distribution, wherein the polymodal particle size distribution comprises a first mode having a first particle size in the range of from 8 to 35 nanometers, wherein the polymodal particle size distribution comprises a second mode having a second particle size in the range of from 2 to 20 nanometers, wherein the first particle size is greater than the second particle size. 
     
     
         19 . The antistatic article of  claim 18 , wherein the amorphous antistatic composition further comprises metal cations, wherein a majority of the metal cations are individually disposed in the amorphous silica matrix, and wherein the metal cations comprise from 0.5 to 20 mole percent of the total combined moles of silicon and metal cations in the composition. 
     
     
         20 . The antistatic article of  claim 19 , wherein the metal cations are selected from the group consisting of manganese cations, silver cations, vanadium cations, tin cations, platinum cations, and combinations thereof 
     
     
         21 . The antistatic article of  claim 19 , wherein the metal cations are selected from the group consisting of silver cations, vanadium cations, and combinations thereof. 
     
     
         22 . The antistatic article of  claim 18 , wherein the substrate comprises glass or an organic polymer. 
     
     
         23 . The antistatic article of  claim 18 , wherein the organic polymer comprises polyethylene terephthalate. 
     
     
         24 . The antistatic article of  claim 18 , wherein the antistatic layer is optically clear. 
     
     
         25 . The antistatic article of  claim 18 , wherein the antistatic layer has a thickness in a range of from 0.02 to 100 microns. 
     
     
         26 . The antistatic article of  claim 18 , wherein the coatable composition is essentially free of organic non-volatile compounds.