51动漫

When vandals scratch windows with diamond rings or other hard objects it can
take hours to grind and polish, or replace the damaged glass. Now 3M of St Paul,
Minnesota, has a better way of repairing such 鈥渟cratchiti鈥�. In WO 00/24576 it
describes a multilayered sandwich of thin, transparent polycarbonate sheets
stuck together with medium-strength adhesive. A stronger adhesive keeps the
stack attached to the window. When vandals strike, clean-up workers use a sticky
wand to remove the top sheet of the stack. This exposes the untouched sheets
beneath, leaving the window clear.