If the columns are data type NUMERIC, then removal of leading zeros is the correct behavior. You can’t expect a tool to work incorrectly just for some columns that you’d like to handle differently from others.
You have alternatives:<ol>
<li>Don’t use CPYTOIMPF. Write your own programs.</li><li>Create a view that formats the NUMERIC columns as CHAR columns in whatever format you choose. Use CPYTOIMPF over the view instead of over the table.</li><li>Use the Qshell db2 utility to construct a .CSV or another kind of streamfile. Like the view, your SELECT statement can create whatever kind of output you want.</li>
(There may be others.)
However you proceed, be aware that every tool is going to work according to how you define your database. You must adjust accordingly. If you don’t want NUMERIC columns treated as numeric, then define them as a different data type. A view can CAST() columns to different data types, but you have to create the instructions.