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US 2009/0022927 A1Published application
Flame-perforated films having controlled tear characteristics and methods, systems, and apparatus for making same
Assignee3M Innovative Properties Company
InventorsMark A. Strobel, Michael J. Ulsh, Joel A. Getschel
Life of this patent
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Abstract
The disclosure is directed to methods, systems, and apparatus for obtaining flame-perforated films which reduce or eliminate skewing of perforations in such films caused by thermal creep, whereby the film has perforations arranged to provide controlled tear characteristics, especially in both the lengthwise or machine direction (MD), and the crosswise or transverse direction (TD).
Claims31
A method of correcting for positional skewing of perforations from a predefined angle of inclination relative to a generally transverse reference line of flame-perforated film produced by a flame-perforating process under a first set of conditions, the method comprising:
- determining the degree of angular deviation of the major axis of each of the one or more perforations in the flame-perforated film from the predefined angle of inclination;
- and forming one or more perforation-forming structures in a film supporting structure adapted for use in a subsequent flame-perforating process using the first set of conditions, wherein each of the perforation-forming structures has a major axis being angularly offset to the predefined angle of inclination by an inverse amount related to the angular deviation of the one or more corresponding perforations of the previously flame-perforated film.
A film-supporting apparatus adapted to form perforations in film supported thereon during a flame-perforating process, wherein each of the formed perforations has a major axis positioned at a predefined angle of inclination relative to a generally transverse reference line, the apparatus comprises:
- a body having a film supporting surface, and one or more perforation-forming structures positioned on the film supporting surface, wherein each perforation-forming structure has a major axis angularly offset from the predefined angle of inclination of the major axis of each corresponding formed perforation by a predetermined amount.
A roller adapted for forming perforations in flame-perforated film, the roller comprises:
- a body having a film supporting surface;
- and one or more perforation-forming structures on the film supporting surface and positioned to form corresponding perforations in the film during a flame-perforating process, such that each formed perforation has a major axis at about 45 degrees relative to a generally transverse reference line to the film, wherein each perforation-forming structure has a major axis positioned at a predefined angular offset from the 45 degrees.
A roller adapted for use in a flame-perforating apparatus for perforating film, the roller comprises:
- a body;
- a film supporting surface on the body adapted to support and convey film to be perforated;
- and one or more perforation-forming structures on the supporting surface, each of which has a major axis having an angular orientation that is angularly offset to a predefined angle of inclination that is established relative to a generally transverse reference line across the film to be supported, wherein the angular offset is inversely related to a predefined angular deviation of one or more corresponding skewed perforations formed in previous flame-perforated film that relate to film to be flame-perforated, the film supporting surface thus configured forms perforations in the film to be flame-perforated during a flame-perforating process that offsets the impact of thermal creep skewing the resulting one or more perforations, such that the major axis of each of the resulting one or more formed perforations is generally coincident with the predefined angle of inclination.
A method of controlling tear characteristics of film, comprising:
- providing a polymeric film to be flame-perforated;
- providing a flame supporting apparatus that includes a film supporting surface having one or more perforation-forming structures, each of the one or more perforation-forming structures has a major axis with an angular orientation that is angularly offset to a predefined angle of inclination established relative to a generally transverse reference line of the film to be supported by the film supporting surface, wherein the angular offset is by an amount that is inversely related to the angular deviation relative to the predefined angle of inclination of one or more corresponding skewed perforations formed in previous flame-perforated film;
- and applying heat and tension forces to the film as it is advanced by the film supporting apparatus to form resulting perforations in the film;
- such that the film supporting surface thus configured forms perforations in the film supported thereby that offset the impact of thermal creep skewing the one or more resulting perforations, whereby the major axis of each of the resulting one or more perforations is generally coincident with the predefined angle of inclination.
1 more element
A flame-perforated film comprising:
- first and second major surfaces;
- one or more perforations formed in at least one of the first and second major surfaces, wherein the one or more perforations in the film is formed by providing a film supporting apparatus that includes a film supporting surface having one or more perforation-forming structures thereon, each of the perforation-forming structures has a major axis with an angular orientation that is angularly offset to a predefined angle of inclination established relative to a generally transverse reference line of film to be supported by the film supporting surface, wherein the angular offset is by an amount that is inversely related to the angular deviation relative to the predefined angle of inclination of one or more corresponding skewed perforations formed in previous flame-perforated film;
- and applying heat and tension forces to the film as it is advanced by the film supporting apparatus such that the film supporting surface thus configured forms perforations in the film supported thereby during a flame-perforating process that offsets the impact of thermal creep skewing the resulting one or more perforations, such that the major axis of each of the resulting one or more formed perforations is generally coincident with the predefined angle of inclination.
A flame-perforating apparatus for flame-perforating a film;
- the flame-perforating apparatus comprises:
- a frame;
- a first device coupled to the frame for applying heat to the film to form perforations in the film;
- and a second device coupled to the frame for advancing the film under tension through the apparatus, the second device includes a film supporting apparatus, the flame supporting apparatus includes a body having one or more perforation-forming structures on a film supporting surface thereof, each of the perforation-forming structures has a major axis with angular orientation angularly offset to a predefined angle of inclination established relative to a generally transverse reference line of film to be supported by the film supporting surface, wherein the angular offset is by an amount that is inversely related to the angular deviation relative to the predefined angle of inclination of one or more corresponding skewed perforations formed in previous flame-perforated film.
1 more element
A system for flame-perforating film, the system comprises:
- a film including first and second major surfaces;
- one or more perforations formed in at least one of the first and second major surfaces;
- and a flame-perforating apparatus for flame-perforating the film;
- the flame-perforating apparatus including:
- a first device for applying heat to the film to form perforations in the film;
- and a second device for advancing the film under tension through the flame-perforating apparatus, the second device includes a film supporting apparatus, the flame supporting apparatus includes a body having one or more perforation-forming structures on a film supporting surface thereof, each of the perforation-forming structures has a major axis with an angular orientation that is angularly offset to a predefined angle of inclination established relative to a generally transverse reference line of film to be supported by the film supporting surface, wherein the angular offset is by an amount that is inversely related to the angular deviation relative to the predefined angle of inclination of one or more corresponding skewed perforations formed in previous flame-perforated film.
3 more elements
Dependencies are inferred from the claim text.