Nano-structured surface coating process, nano-structured coatings and articles comprising the coating

Abstract

The invention relates to a new process for the preparation of nano-structured and/or nano-porous surfaces, coatings having a nano-structured and/or nano-porous surface and articles comprising said coatings. The invention also relates to the use of coatings according to the invention, in particular as anti-reflective coatings. The process for the preparation of the surface nano-structured and/or nano-porous coatings is a process comprising the steps of a) applying a mixture to a substrate which mixture comprises i) reactive nano-particles ii) at least one solvent iii) optionally a compound having at least one polymerisable group, in an amount that results in an increase in the transmission of at least 0.5%, for at least part of the electromagnetic spectrum between 400 and 800 nm, after the mixture has been applied and cured on a transparent substrate, in comparison with the same substrate without a coating b) inducing crosslinking and/or polymerisation in the mixture applied to the substrate.

1 . A coated substrate which comprises a transparent substrate and an anti-reflective coating on the substrate, wherein
 the anti-reflective coating consists of a single layer which is the polymerized product of a mixture comprising:
 i) reactive nano-particles, having reactive organic groups on their surface, 
 ii) at least one solvent 
 iii) optionally a compound having at least one polymerisable group in an amount small enough to allow the formation of a nano-structures and/of nano-porous surface after polymerisation of the mixture, and wherein 
   the single layer anti-reflective coating exhibits an increased transmission by at least 0.5% for at least part of the electromagnetic spectrum between 400 and 800 nm when the coating is present on a transparent substrate in comparison with the same substrate without the coating.   
     
     
         2 . A coated substrate according to  claim 1 , wherein the coating contains an amount of reactive nano-particles between 70-100 wt %, relative to the weight of the coating. 
     
     
         3 . A coated substrate according to  claim 1  wherein the coating has a thickness of between 50-200 nm. 
     
     
         4 . A coated substrate according to  claim 1 , wherein the coating increases the transmission by at least 1% for at least part of the electromagnetic spectrum between 400 and 800 nm if the coating is present on a transparent substrate in comparison with the same substrate without a coating. 
     
     
         5 . A coated substrate according to  claim 1 , wherein the coating increases the transmission by at least 3%. 
     
     
         6 . A coated substrate according to  claim 1 , wherein the coating exhibits a static water contact angle of less than 60°. 
     
     
         7 . A coated substrate according to  claim 1 , wherein the coating exhibits a static water contact angle of less than 40°. 
     
     
         8 . A coated substrate according to  claim 1 , wherein the coating exhibits a static water contact angle of more than 90°. 
     
     
         9 . A coated substrate according to  claim 1 , wherein the coating exhibits a contact angle of more than 140°. 
     
     
         10 . A process for making an antireflective transparent substrate comprising:
 (a) coating a transparent substrate with an anti-reflective coating, wherein the anti-reflective coating consists of a single layer which is a mixture comprising:
 i) reactive nano-particles, having reactive organic groups on their surface, 
 ii) at least one solvent 
 iii) optionally a compound having at least one polymerisable group in an amount small enough to allow the formation of a nano-structures and/of nano-porous surface after polymerisation of the mixture, and wherein 
   (b) polymerizing the mixture on the substrate to obtain a polymerized single layer anti-reflective coating on the substrate which exhibits an increased transmission by at least 0.5% for at least part of the electromagnetic spectrum between 400 and 800 nm when the coating is present on the transparent substrate in comparison with the same substrate without the coating.   
     
     
         11 . The process of  claim 10 , wherein step (b) includes exposing the mixture on the substrate to UV radiation.