Low-color scratch-resistant articles with a multilayer optical film

A cover article comprising:

• a substrate having a surface, and
• an optical film disposed on the substrate surface forming a coated surface, the optical film having a physical thickness in a range from about 0.1 μm to about 3 μm;
• wherein the optical film comprises an average hardness in a range from about 8 GPa to about 30 GPa as measured by a Berkovich Indenter Hardness Test along indentation depths of 100 nm or greater;
• and,
• wherein the cover article exhibits an average transmittance of 85% or greater over the visible spectrum;
• wherein the cover article further comprises a color shift of 2 or less, when viewed at least one incident illumination angle in the range from about 5 degrees to about 60 degrees from normal incidence under an illuminant comprising CIE A illuminants, CIE B illuminants, CIE C illuminants, CIE D illuminants or CIE F illuminants;
• and
• further wherein color shift is determined by the equation √((a*2−a*1)2+(b*2−b*1) 2), where a*1 and b*1 are coordinates of the article when viewed at normal incidence and a*2 and b*2 are coordinates of the article viewed at the at least one incident illumination angle, and wherein the coordinates of the article when viewed at normal incidence and at the at least one incident illumination angle are both in transmittance or reflectance.

A cover article comprising:

• a substrate having a surface;
• an optical film disposed on the substrate surface forming a coated surface, the optical film comprising a scratch-resistant layer and an optical interference layer disposed between the scratch-resistant layer and the substrate;
• wherein the optical interference layer comprises a first low refractive index (RI) sub-layer and a second high refractive index (RI) sub-layer;
• wherein the first low RI sub-layer comprises silicon-containing oxide disposed on the substrate surface;
• wherein the second high RI sub-layer comprises a silicon-containing nitride or a silicon-containing oxynitride;
• wherein the scratch resistant layer comprises a silicon-containing nitride, a silicon-containing oxynitride or SiuAlvOxNy;
• wherein the cover article further comprises a color shift of 2 or less, when viewed at least one incident illumination angle in the range from about 5 degrees to about 60 degrees from normal incidence under an illuminant comprising CIE A illuminants, CIE B illuminants, CIE C illuminants, CIE D illuminants or CIE F illuminants;
• and
• further wherein color shift is determined by the equation √((a*2−a*1)2+(b*2−b*1)2), where a*1 and b*1 are coordinates of the article when viewed at normal incidence and a*2 and b*2 are coordinates of the article viewed at the at least one incident illumination angle, and wherein the coordinates of the article when viewed at normal incidence and at the at least one incident illumination angle are both in transmittance or reflectance.