Silica-based matting agents and methods of making and using the same

A matting agent for aqueous coating compositions, said matting agent comprising composite silica particles consisting of porous silica particles and a coating of (i) one or more waxes, (ii) one or more polymers, or (iii) any combination of (i) and (ii) at least partially within pores of the porous silica particles;

• wherein the porous silica particles have a total pore volume of 0.10 cc/gm to 3 cc/gm prior to coating;
• and the porous silica particles are silica gel, precipitated silica, or fumed silica particles;
• wherein the composite silica particles comprise from 20 wt. % to 50 wt. %, based on a total weight of said composite silica particles, of one of (i) said one or more waxes, (ii) said one or more polymers, or (iii) any combination of (i) and (ii);
• and the composite silica particles have a median particle size of greater than 3.0 microns (μm) up to about 50.0 μm, a total pore volume of less than or equal to about 1.2 cc/gm as determined by Barrett-Joyner-Halenda (BJH) method, and a BET surface area of 25 m2/gm to 210 m2/gm;
• and wherein, when incorporated into an aqueous coating composition in an effective matting amount and the coating composition is applied onto a substrate to form a clear coat film, the matting agent provides increased chemical resistance in the film as compared to a film formed from an aqueous coating composition comprising silica particles having a higher total pore volume as a matting agent.