Fluorine-free hydrophobic and oleophobic nonwoven

Abstract

The invention relates to fluorine-free hydrophobic and oleophobic nonwoven for use, for example, in automotive engine bays, and a method for making such nonwoven.

1 . A method for making a nonwoven fabric having hydrophobic and oleophobic properties, the method comprising the following steps:
 providing a nonwoven fabric comprising fibers;   providing an aqueous colloidal solution comprising nanoscale SiO 2 -particles, which is formed from an aqueous precursor solution comprising a SiO 2 -producing substance; and   applying the colloidal solution onto the nonwoven fabric to form a hydrophobic and oleophobic finish on fibers of the fabric and thereby impart hydrophobic and oleophobic properties.   
     
     
         2 . The method of  claim 1 , wherein the fibers are carded fibers. 
     
     
         3 . The method of  claim 1 , wherein the fibers comprise 50 wt % to 100 wt % synthetic fibers. 
     
     
         4 . The method of  claim 1 , wherein the SiO 2 -producing substance is a silicon alkoxide. 
     
     
         5 . The method of  claim 1 , wherein the solvent of the aqueous precursor solution is water or a mixture of alcohol and water. 
     
     
         6 . The method of  claim 1 , wherein the aqueous precursor solution comprises a hydrolysis and condensation catalyst. 
     
     
         7 . The method of  claim 1 , wherein the solids content in the colloidal solution is between 0.1 and 15 wt %. 
     
     
         8 . The method of  claim 1 , wherein the colloidal solution is applied onto the surface of the nonwoven fabric by spray application, coating or by foaming. 
     
     
         9 . The method of  claim 1 , wherein the amount of colloidal solution applied to the nonwoven fabric is between 0.1 g/m 2  and 5 g/m 2 . 
     
     
         10 . A nonwoven fabric comprising a surface having a hydrophobic and oleophobic properties, wherein the nonwoven fabric comprises fibers and wherein a hydrophobic and oleophobic finish is present on fibers of the fabric, thereby imparting hydrophobic and oleophobic properties to the fabric, wherein the finish comprises a continuous or interrupted porous SiO 2 -containing layer of nanoscale thickness. 
     
     
         11 . The nonwoven fabric of  claim 10 , wherein the layer has a thickness of 10 to 300 nm. 
     
     
         12 . The nonwoven fabric of  claim 10 , wherein the surface free energy of the surface having a hydrophobic and oleophobic properties is 24 mN/m or lower. 
     
     
         13 . The nonwoven fabric of  claim 10 , wherein the porous SiO 2 -containing layer comprises structural elements from SiO 2 , RSiO 1.5 , and/or R 2 SiO, where R═H, alkyl, aryl, epoxy-alkyl, or aminoalkyl. 
     
     
         14 . An automotive article, said article comprising the nonwoven fabric according  claim 10 . 
     
     
         15 . The method of  claim 1 , wherein the fibers are carded fibers and providing the nonwoven fabric includes carding and laydown of the carded web on a conveyor of a production line. 
     
     
         16 . The method of  claim 1 , wherein the fibers are carded fibers and providing the nonwoven fabric includes carding and laydown of the carded web on a conveyor of a production line involving cross-laying the carded web. 
     
     
         17 . The method of  claim 1 , wherein the fibers comprise 50 wt % to 100 wt % synthetic fibers and formed from polypropylene, polyethylene, polyethylene terephthalate, polyacrylate, polyacrylonitrile, polyamide, or a mixture thereof. 
     
     
         18 . The method of  claim 1 , wherein the SiO 2 -producing substance is a silicon alkoxide that is selected from one or more of a tetraalkoxysilane, an alkyltrialkoxysilane, a dialkyldialkoxysilane, or any mixture thereof, preferably alkyltriethoxysilanes or aminopropyltriethoxysilanes. 
     
     
         19 . The method of  claim 1 , wherein the solids content in the colloidal solution is between 1 and 7 wt %. 
     
     
         20 . The method of  claim 1 , wherein the amount of colloidal solution applied to the nonwoven fabric is between 0.5 g/m 2  and 2 g/m 2 .