Needle size for invisible thread
What size sewing machine needle should I use with monofilament thread?
I suggest starting with an 80/12 in either a Topstitching or Microtex Sharp needle. As you become confident in your machine quilting skills, then I would move down to a 70/10 or even a 60/8.
The monofilament thread doesn't fill the needle hole like a thread made from several plies will. The plies relax after the stitch is complete and fill in the space.
The smaller needle makes a smaller hole which I like. But...
...I liken quilting with a 60/8 to quilting with a 'staple'.
They are fine, so very, very fine.
If you're free motion quilting and pull the sandwich too fast, they are easy to break. There have been days where I've literally broken a whole package of needles before I 'settled' into my quilting frame of mind, so I've always got a supply of these teeny needles on hand. Remember to stock up when they're on sale.
Thank you for your question.