Just a P2 thought and another perspective on Lois' interesting question.
While hot melt glues may be better environmentally than most or all other
glues, what about considering non-glue alternatives to binding? Some of
those alternatives, such as staples and certain binders, would be better for
the environment and recycling. I do realize that not all products are
created equal so, perhaps for some, glues are necessary. But when glues are
not required, there are other non-chemical binding options.