Method of making light-blocking high opacity articles

A method for providing a foamed, opacifying element, the method consisting essentially of, in order:

• providing a foamable aqueous composition that has at least 35% solids and up to and including 70% solids, and consists essentially of:
• (a) at least 0.05 weight % and up to and including 15 weight % of porous particles, each porous particle comprising a continuous polymeric phase and a first set of discrete pores dispersed within the continuous polymeric phase, the porous particles having a mode particle size of at least 2 μm and up to and including 50 μm;
• (b) at least 20 weight % and up to and including 70 weight % of a binder material having a glass transition temperature (Tg) of less than 25° C.;
• (c) at least 0.0001 weight % and up to and including 30 weight % of one or more additives comprising a surfactant;
• (d) water;
• (e) at least 0.001 weight % of an opacifying colorant different from all the one or more (c) additives, which opacifying colorant absorbs electromagnetic radiation having a wavelength of at least 380 nm and up to and including 800 nm,
• all amounts based on the total weight of the foamable aqueous composition;
• aerating the foamable aqueous composition to provide a foamed aqueous composition having a foam density of at least 0.1 g/cm3 and up to and including 0.5 g/cm3;
• disposing the foamed aqueous composition onto a surface of at least one supporting side of a porous substrate;
• drying the foamed aqueous composition, without substantial curing of the binder material, to provide a dry foamed composition on the surface;
• densifying the dry foamed composition by subjecting the dry foamed composition to mechanical pressure to reduce its thickness, to provide a dry opacifying layer in a foamed, opacifying element having a light-blocking value (LBV) of at least 4;
• and
• curing the dry opacifying layer in the foamed, opacifying element to convert the (b) binder material to a (b′) matrix material.