To obtain a coating composition for primer coat comprising a specific organosilane component, silica and/or alumina, excellent in storage stability and appearance of coating film, adhesiveness, weather resistance, etc., having high hardness and capable of preventing deterioration of base or substrate and improving adhesiveness between the substrate and top coat layer.
This coating composition for primer coat comprises (1) (a1) at least one kind of compound selected from an organosilane represented by the formula (R1)nSi(OR2)1-n [R1 are same or different when two R1 are present and each represents 1-8C monovalent organic groups; R2 are same or different and each represents a 1-5C alkyl group or a 1-6C acyl group; (n) is an integer of 0-2], a hydrolyzate of the above organosilane and a condensation product of the above organosilane and (b) colloidal silica and/or colloidal alumina or (2) the above (a1) component and (a2) a polymer containing a silyl group having silicon atom bonded to a hydrolyzable group and/or hydroxyl group and (b) colloidal silica and/or colloidal alumina.
HONDA YOSHIKAZU
SAKAGAMI TOSHIKI
