When you user sc_redir the application stop running the code directly after sc_redir, because you are redirecting to another application.
You can do the following,
Write the code of the blank application in the onValidateSuccess event (not recommendet but it works)
or you gather all Document id in an array and give the array to the blank application and loop though the array in the blank application and send the documents there to a printer.
But you can not display each document and then print it because each document will be opend in the same window and only the last one will be visible.
So you have to use a jquery plugin for printing or a network Printer where you can send the document without displaying it on the screen.
Or you put all documents in one PDF and then display this PDF (witch contain all Documents) and then print it