Most of the embroidered patches you find today have a backing with heat activated glue. Manufacturers make patches this way so they're easy to mount using only a hot iron. But sometimes people need patches with just a simple cloth or plastic backing.
Without the glue users have to find other ways of mounting the patches. If they're being applied to clothing the most secure way is with needle and thread. A classic overhand stitch takes the thread around the border and through the fabric for a secure fit that won't allow the patch to slide. Others use just a simple stitch or two in a few strategic places around the perimeter. The second method is better in situations where patches are changed frequently.
For a really temporary patch some manufacturers sell them with button loops sewn in. The loops allow you to attach the patch using any standard button and button hole. The only problem with this type of mounting is the fact that the patch does not lay flat. Even a slight breeze can lift it up and toss it around.
One other method of attaching embroidered patches without glue is to purchase them with pre-mounted pins. In essence, this type of patch is nothing more than the old-fashioned button except that it's made out of fabric rather than aluminum or plastic. These are great for uniforms that require the patch to lay flat but still be easily removed and replaced.
If you can't find embroidered patches without heat activated glue, and you're worried about the glue damaging fabric underneath, it's best to prevent the garment from being exposed to intense heat. That means don't put it in the dryer and don't leave it lying out in the sun for long periods of time.
