OPTICAL ARTICLE COMPRISING AN ANTI-REFLECTING COATING HAVING ANTI-FOGGING PROPERTIES

An optical article having anti-fogging properties, comprising a substrate having one main face coated with an anti-reflecting stack of layers of low refractive index (Ll) and high refractive index (HI) including an outermost and innermost layer, wherein the outermost layer of the anti-reflecting stack is a sandwich layer comprising a core portion interleaved between two side portions, said core portion being made of SiO2, SiOx with 1 =x2 and SiOx or a mixture of SiO2 and/or SiOx with 10% by weight or less, based on the total weight of the mixture, of AI2O3, having a physical thickness ranging from 20 to 150 nm, preferably 30 to 80 nm and being formed by vacuum evaporation deposition in a vacuum chamber at a deposition rate of at least 1.10 nm/s and/or maintaining a pressure higher than or equal to 1 x10-4 mbar, preferably ranging from 1.2 x 10-4 mbar to 5 x 10-4 mbar in said vacuum chamber during deposition by introducing inside said vacuum chamber at least one gas selected from the group consisting of oxygen, an inert gas or a mixture thereof, said gas pressure, the side portions being made of a material selected from the same materials as for the core portion, having a physical thickness of 1 to 50 nm, preferably from 2 to 20 nm and being formed by vacuum evaporation deposition at a deposition rate of less than 1.10 nm/s and maintaining a pressure ranging from 1 x10-5 mbar to less than 1 x 10-4 mbar, preferably 0.2 x 10-4 mbar 0.5 x10-4 mbar inside the vacuum chamber, optionally by introducing at least one gas selected from the same group as for the core portion, and, wherein the innermost layer is made of a material selected from the same group as for the core portion of the outermost layer, said innermost layer having a physical thickness ranging from 50 to 500 nm, preferably 100 to 300 nm and being formed by vacuum evaporation deposition at a deposition rate of at least 1.10 nm/s and/or maintaining a pressure higher than or equal to 1 x10-4 mbar, preferably ranging from 1.2 x 10-4 mbar to 5 x 10-4 mbar in said vacuum chamber by introducing inside said vacuum chamber at least one gas selected from the group consisting of oxygen, an inert gas or a mixture thereof. La présente invention concerne un article optique ayant des propriétés antibuée, comportant un substrat présentant une face principale revêtue d'une superposition de couches antireflet de faible indice de réfraction (L1) et d'indice de réfraction élevé (HI) comprenant une couche à l'extrémité