Liquid tank, viewing device for under-liquid observation, and optical film

Abstract

A liquid tank, a viewing device for under-liquid observation, and an optical film are disclosed, each excellent in visibility and durability and being easy to clean. In at least one embodiment of the present invention is directed to a liquid tank having a transparent wall, including, on an internal surface of the wall, a first moth-eye layer having a moth-eye structure, and a protective layer covering the moth-eye structure, in this order from the wall side, and preferably, further including, on an external surface of the wall, a second moth-eye layer having a moth-eye structure, and the second moth-eye layer being disposed in a region facing the first moth-eye layer.

1 . A liquid tank having a transparent wall,
 comprising, on an internal surface of the wall,   a first moth-eye layer having a moth-eye structure, and   a protective layer covering the moth-eye structure, in this order from the wall side.   
     
     
         2 . The liquid tank according to  claim 1 ,
 further comprising, on an external surface of the wall,   a second moth-eye layer having a moth-eye structure, and   the second moth-eye layer being disposed in a region facing the first moth-eye layer.   
     
     
         3 . The liquid tank according to  claim 1 ,
 wherein the protective layer contains a fluorine-containing resin.   
     
     
         4 . The liquid tank according to  claim 1 ,
 wherein the protective layer has a refractive index substantially equivalent to that of a liquid to be stored in the tank.   
     
     
         5 . The liquid tank according to  claim 1 ,
 wherein the protective layer has a refractive index substantially equivalent to that of water.   
     
     
         6 . The liquid tank according to  claim 1 ,
 wherein the protective layer has a refractive index smaller than that of each of the transparent wall and the first moth-eye layer.   
     
     
         7 . The liquid tank according to  claim 1 ,
 wherein the protective layer has a refractive index of 1.28 to 1.38.   
     
     
         8 . An optical film attached to an internal surface of a liquid tank having a transparent wall,
 the film comprising a moth-eye layer having a moth-eye structure and a protective layer covering the moth-eye structure.   
     
     
         9 . The optical film according to  claim 8 ,
 wherein the protective layer contains a fluorine-containing resin.   
     
     
         10 . The optical film according to  claim 8 ,
 wherein the protective layer has a refractive index substantially equivalent to that of a liquid to be stored in the tank.   
     
     
         11 . The optical film according to  claim 8 ,
 wherein the protective layer has a refractive index substantially equivalent to that of water.   
     
     
         12 . The optical film according to  claim 8 ,
 wherein the protective layer has a refractive index smaller than that each of the transparent wall and the moth-eye layer.   
     
     
         13 . The optical film according to  claim 8 ,
 wherein the protective layer has a refractive index of 1.28 to 1.38.   
     
     
         14 . A viewing device having a transparent window for under-liquid observation,
 the device comprising, on an outer surface of the window, a first moth-eye layer having a moth-eye structure, and   a protective layer covering the moth-eye structure, in this order from the window side.   
     
     
         15 . The viewing device according to  claim 14 ,
 further comprising, on an inner surface of the window, a second moth-eye layer having a moth-eye structure, and   the second moth-eye layer being disposed in a region facing the first moth-eye layer.   
     
     
         16 . The viewing device according to  claim 14 ,
 wherein the protective layer contains a fluorine-containing resin.   
     
     
         17 . The viewing device according to  claim 14 ,
 wherein the protective layer has a refractive index substantially equivalent to that of a liquid to be in contact with the device.   
     
     
         18 . The viewing device according to  claim 14 ,
 wherein the protective layer has a refractive index substantially equivalent to that of water.   
     
     
         19 . The viewing device according to  claim 14 ,
 wherein the protective layer has a refractive index smaller than that of each of the transparent window and the first moth-eye layer.   
     
     
         20 . The viewing device according to  claim 14 ,
 wherein the protective layer has a refractive index of 1.28 to 1.38.   
     
     
         21 . An optical film attached to an outer surface of a viewing device having a transparent window for under-liquid observation,
 the film comprising a moth-eye layer having a moth-eye structure and a protective layer covering the moth-eye structure.   
     
     
         22 . The optical film according to  claim 21 ,
 wherein the protective layer contains a fluorine-containing resin.   
     
     
         23 . The optical film according to  claim 21 ,
 wherein the protective layer has a refractive index substantially equivalent to that of a liquid to be in contact with the device.   
     
     
         24 . The optical film according to  claim 21 ,
 wherein the protective layer has a refractive index substantially equivalent to that of water.   
     
     
         25 . The optical film according to  claim 21 ,
 wherein the protective layer has a refractive index smaller than that of each of the transparent window and the moth-eye layer.   
     
     
         26 . The optical film according to  claim 21 ,
 wherein the protective layer has a refractive index of 1.28 to 1.38.