Ignore collision at high velocity.

I need to allow a collider to pass through another when it is moving at a high enough speed. it is a very simple problem but I cant find a solution. This is unity 2d. There is no physics ignore collision. I tried setting up a trigger in front of the collider to move tthe object to a layer that didn't collide, but it doesn't seem to happen fast enough because they still collide the first time. I need the objects to ignore the effects of the collision until it is over. Any help would be greatly appreciated.