Process for high-speed production of webs of debossed and perforated thermoplastic film

A process for debossing and perforating a substantially continuous web of substantially planar thermoplastic film, using a forming structure having a patterned forming surface with holes and an opposed surface, said forming structure being open from said holes in said forming surface to said opposed surface, said web of film having an indefinite length, a first surface, a second surface, and a thickness, said thickness being the distance between said first surface and said second surface, said film having a melt temperature range, which process comprises the steps of:

• (a) providing said web of substantially planar film with said first surface of said web of film proximate said forming surface, said forming structure moving in a direction of said length of said web of film and carrying said web of film in said direction, said web of film being substantially entirely molten;
• (b) substantially continuously applying a vacuum from a vacuum source to said opposed surface of said forming structure from a first position along said direction of movement of said forming structure to a second position, said first and second positions being fixed proximate said opposed surface of said moving forming structure whereby said opposed surface continually moves past said first and second positions, said vacuum being sufficiently great to cause said first surface of said web of film to be urged against said forming surface;
• to cause perforations to be created in said web of film, whereby a web of debossed and perforated film is formed in the image of said forming surface from said web of substantially planar film, said web of debossed and perforated film having a first surface and a second surface corresponding to said first surface and said second surface, respectively, of said web of substantially planar film;
• and to hold said web of debossed and perforated film against said forming surface without permitting substantial spring-back of said debossed and peforated film;
• and
• (c) applying cooling fluid to said second surface of said web of debossed and perforated film and drawing said cooling fluid through said perforations of said web of debossed and perforated film and through said holes in said forming surface with said vacuum, such that said web of debossed and perforated film is cooled and is set without permitting substantial spring-back of said debossed and perforated film by the time said web of debossed and perforated film passes said second position.

An apparatus for debossing and perforating a substantially continuous web of thermoplastic film having an indefinite length, said apparatus comprising:

• (a) a forming structure having a patterned forming surface with holes and an opposed surface, said forming structure being open from said holes in said forming surface to said opposed surface;
• (b) means for moving said forming structure in a direction of said length of said web of film;
• (c) a stationary vacuum manifold, said manifold being constructed and positioned proximate said opposed surface of said forming structure, such that a vacuum can be drawn substantially continuously on each of said holes of said forming surface while said each hole moves from a first position proximate a first edge of said vacuum manifold to a second position proximate a second edge of said vacuum manifold along said direction of movement of said forming structure;
• and
• (d) means for applying a cooling fluid to said forming surface of said forming structure between said first edge and said second edge of said vacuum manifold, said means for applying said cooling fluid being positioned such that said cooling fluid can be applied to said web of film only after said web of film is debossed and perforated.