Curable composition for glass substitute

A curable composition used instead of glass comprising

• a cationically curable compound;
• a radically curable compound;
• a cationic polymerization initiator comprising a cation of the following Chemical Formula 1;
• and a radical polymerization initiator,
• wherein 3,4,3′,4′-diepoxybicyclohexyl is included in an amount of 60 wt % to 100 wt %, based on the total weight of the cationically curable compound:
• R1-A1R2]k [Chemical Formula 1]
• in the Chemical Formula 1,
• A1 is N, P or S,
• R1 is a C1-20 alkyl or a C2-20 alkenyl radical,
• R2 is a C1-20 alkyl, a C2-20 alkenyl, a C6-30 aryl, a C7-35 alkylaryl or a C7-35 arylalkyl, or a radical in which a hydroxyl, a C1-20 alkyl, a C2-20 alkenyl, a C6-30 aryl, a C7-35 alkylaryl, or a C7-35 arylalkyl is linked to the above radical by a single bond, —O—, —S—, —CO—, —COO— or —OCO—, and
• k is 2 or 3.