Lay-flat soft binding has been around since the '90s. Here's one description:
Lay-Flat Adhesive Binding
And I believe this is the patent for it, which includes images in the PDF:
Lay-flat book binding - Patent 5456496
Lay-flat soft binding has been around since the '90s. Here's one description:
Lay-Flat Adhesive Binding
And I believe this is the patent for it, which includes images in the PDF:
Lay-flat book binding - Patent 5456496