Optical article comprising a temporary antifog coating based on sorbitan surfactants

An optical article comprising a substrate having at least one main surface coated with an antireflection coating and, directly contacting said antireflection coating, a precursor coating of an antifog coating obtained through the grafting on said antireflection coating of at least one compound B bearing a polyoxyalkylene group, said coating precursor of the antifog coating being coated with a surfactant film so as to form an antifog coating, characterized in that said surfactant film contains at least one surfactant A having a sorbitan ring with n of its four hydroxyl groups functionalized with the same or different OH-terminated polyoxyalkylene groups, and p of its four hydroxyl groups functionalized with the same or different R1 groups of formula:

• —(RdO)z—(Y)n2—R′
• in which Rd is an alkylene group, z is an integer ≧1, Y is a divalent group, n2 is 0 or 1 and R′ is a saturated hydrocarbon group having from 12 to 19, preferably 13 to 19 carbon atoms, n and p being integers such that n=2 or 3 and p=1 or 2 with n+p=4.

An optical article comprising a substrate having at least one main surface coated with an antireflection coating, and directly contacting said antireflection coating a precursor coating of an antifog coating, wherein said antireflection coating displays a residual color when no surfactant film is applied onto said coating precursor of the antifog coating and a modified residual color when a film of a surfactant capable of modifying the residual color displayed by said antireflection coating is applied onto said coating precursor of the antifog coating,

• characterized in that said coating precursor of the antifog coating is coated with a film of surfactant capable of modifying the residual color displayed by said antireflection coating so as to form an antifog coating.

A method for determining whether a spectacle lens exhibits antifog properties and, if needed, imparting antifog properties to said spectacle lens, comprising:

• providing a spectacle lens comprising a substrate having at least one main surface coated with an antireflection coating, and directly contacting said antireflection coating a precursor coating of an antifog coating, wherein said antireflection coating displays a residual color when no surfactant film is applied onto said coating precursor of the antifog coating and a modified residual color when a film of a surfactant capable of modifying the residual color displayed by said antireflection coating is applied onto said coating precursor of the antifog coating,
• determining visually which residual color is displayed by said antireflection coating, and
• if at least part of the antireflection coating does not display the modified residual color, applying an additional amount of surfactant capable of modifying the residual color displayed by said antireflection coating on said at least part of the coating precursor of the antifog coating so as to restore the antifog properties of the spectacle lens.