Room temperature curable polyoranopolysloxane silicone sealant composition, the silicone sealant and method for preparing thereof

A room temperature curable composition for a silicone sealant, comprising:

• 30 to 70 wt. % of polyorganosiloxane polymer with a viscosity of 1,500 to 100,000 cSt at 25° C.;
• 5 to 20 wt. % of branched silicone oil with a viscosity of 25 to 10,000 cSt at 25° C.;
• 0.1 to 4 wt. % of two or more cross-linking compounds, each of the cross-linking compounds having two to three reactive groups being reactive with silicon-bonded hydroxyl groups of the polyorganosiloxane polymer;
• 0.01 to 5 wt. % of one or more tin-free catalysts, wherein the one or more tin-free catalysts comprise titanium compounds selected from one or more of tetrabutyl titanate, isopropyl titanate, titanium chelates complex, or any complexes thereof;
• 30 to 70 wt. % of one or more inorganic inert nanofillers;
• and
• 0 to 5 wt. % of one or more functional nanofillers,
• wherein the silicone sealant has a tack free time of equal to or less than 30 minutes according to ASTM C679, and a cured silicone sealant has a tensile adhesive strength on a wet substrate at 65 psi or higher according to ISO 8339, and stain-resistance where the stain in terms of width and depth on a substrate is substantially absent according to the ASTM C1248 when the silicone sealant is applied on the substrate and cured at room temperature for 21 days before being subjected into an oven with a temperature of about 70° C.