You export it as a Wavefront (*.obj) file in blender. Then in the Export Window you select: "Limit to [X] Selection Only".
This obj-File you can import in UnionBytes Painter.
thanks i am using it now. Suggestion, add wireframe option on 3d model. Add channel views to 3d model (same as 2d/UV)
Thank you for the Feedback, I will write it to my ToDo list. From which I evaluate what to do next from Update to Update.