Fire resistant insulation

Does anyone know if its possible to buy fire resistant insulation so that I can make an existing metal box fire resistant (delay the heating of the content of the box in the event of a fire). I am not looking for a fireproof box, but just something that is fire resistant… I need it to store materials that are flammable therefore needs to be stored inside such a box…

I am no expert, but doesn’t a safe have those fire proof properties?

A safe that’s fireproof and bigger than a tiny closet (for storing money and jewelries) costs over 30,000nt. Its way out of my price range. I am not looking for something fireproof, just to buy some time in case of a fire.