Method for making light-blocking articles

A method for preparing a foamed, opacifying element having a single dry foamed opacifying layer, the method comprising the steps of:

• A) providing a substrate having a first opposing side and a second opposing side,
• B) applying a foamed aqueous composition onto the first opposing side of the substrate,
• C) drying the applied foamed aqueous composition, to provide a single dry foamed opacifying layer,
• D) densifying the single dry foamed opacifying layer to reduce its thickness by at least 20% compared to its original thickness;
• E) applying a non-foamed functional composition formulation comprising (i) glass particles, to the single dry foamed opacifying layer, and
• F) curing the applied non-foamed functional composition formulation and the single dry foamed opacifying layer to provide a non-foamed functional layer as the outermost layer on the single dry foamed opacifying layer,
• thereby providing the foamed, opacifying element having a single dry foamed opacifying layer,
• wherein:
• the single dry foamed opacifying layer comprises:
• (a) at least 0.1 weight % and up to and including 35 weight % of porous particles, each porous particle comprising a continuous polymeric phase and 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 10 weight % and up to and including 80 weight % of a matrix material that is derived from a (b) binder material having a glass transition temperature (Tg) of less than 25° C.;
• (c) at least 0.0001 weight % and up to and including 50 weight % of one or more additives selected from the group consisting of dispersants, foaming agents, foam stabilizing agents, plasticizers, flame retardants, optical brighteners, thickeners, biocides, tinting colorants, metal particles, and inert inorganic or organic fillers;
• (d) less than 5 weight % of water, and
• (e) at least 0.002 weight % of an opacifying colorant different from all of the one or more additives of (c), which opacifying colorant absorbs electromagnetic radiation having a wavelength of at least 380 nm and up to and including 800 nm,
• all amounts being based on the total weight of the single dry foamed opacifying layer.