Preparation method for composite transparent hard coating

The present invention discloses a preparation method for a composite transparent hard coating. The method comprises: mixing organic siloxane, water and an inorganic acid; carrying out high-speed stirring at a room temperature to obtain hydrolyzed organic siloxane; then adding aluminum isopropoxide and water; heating to the temperature of 75-85 DEG C under a stirring condition; holding the temperature for 10-15 hours to obtain a component A; mixing tetraethoxysilane, water, ethanol and nitric acid; stirring at the room temperature until the resulting mixture is clear to obtain a component B; mixing the component A and the component B to prepare a composite sol; coating the composite sol on a substrate; carrying out air drying for 0.5 hour; heating to the temperature of 105-120 DEG C and curing for 1.5-2.5 hours to obtain the composite transparent hard coating. According to the present invention, the pencil hardness of the composite transparent hard coating can achieve 6 H; the composite transparent hard coating can be adopted as the protection layer for the optical material; with the method of the present invention, the process is simplified, the industrial production is improved, the cost is reduced, and the method has broad application prospects in a plurality of industrial fields and daily life.