Elastic film and method for producing an elastic layer material
View Patent ↗An elastic film has a perforation formed by perforation holes that are elongated along a preferred expanding direction in the unexpanded state, wherein the ratio of the length of the perforation holes determined along the preferred expanding direction to a width of the perforation holes determined perpendicular thereto amounts to at least 3:2. The elongation at break along the preferred expanding direction is at least twice as high as the elongation at break determined perpendicular thereto along the width of the perforation holes.
1. An elastic film with a perforation formed by laser-generated perforation holes that are elongated along a preferred expanding direction in an unexpanded state and have a bulge with an increased thickness (d′) that runs around each of the perforation holes, wherein a ratio of a length of each of the perforation holes determined along the preferred expanding direction to a width of each of the perforation holes determined perpendicular thereto amounts to at least 3:2, and wherein an elongation at break along the preferred expanding direction is at least twice as high as the elongation at break determined perpendicular thereto along the width of the perforation holes.
2. The elastic film according to claim 1 , wherein the perforation holes each have a surface area of between 0.05 mm 2 and 1 mm 2 .
3. The elastic film according to claim 1 , wherein a thickness (d) of the film amounts to between 15 μm and 70 μm.
4. The elastic film according to claim 1 , wherein the elongation at break along the preferred expanding direction amounts to at least 600%.
5. The elastic film according to claim 1 , wherein the elongation at break perpendicular to the preferred expanding direction is between 110% and 300%.
6. The elastic film according to claim 1 , wherein the elastic film comprises at least one strip provided with the perforation holes, and an unperforated strip that alternates with the at least one strip with the perforation holes along the preferred expanding direction or perpendicular to the preferred expanding direction.
7. The elastic film according to claim 1 , wherein the preferred expanding direction is oriented perpendicular to a production/processing direction.
8. The elastic film according to claim 1 , wherein at least one elastic film layer of the elastic film is formed from styrene block copolymer.
9. The elastic film according to claim 1 , wherein a hole area percentage of the perforation amounts to between 0.5% and 10%.
10. A method for producing an elastic layer material, comprising:
guiding an elastic film along a production direction, and
creating a perforation in the elastic material by forming a plurality of perforation holes by means of laser radiation such that, to generate each perforation hole, an associated laser beam is moved over the elastic film over a length of at least 200 μm in a relative movement along a preferred expanding direction of the elastic film, and the perforation holes accordingly obtain a shape that is elongated along the preferred expanding direction and have a bulge of increased thickness that runs around each of the perforation holes, wherein a ratio of a length of each of the perforation holes determined along the preferred expanding direction to a width of each of the perforation holes determined perpendicular thereto amounts to at least 3:2, and wherein an elongation at break along the preferred expanding direction of at least twice as high as the elongation at break determined perpendicular thereto along the width of the perforation holes.
11. The method according to claim 10 , wherein the preferred expanding direction extends perpendicular to the production direction along a transverse direction (CD), and the elastic film is free from tensile forces in the transverse direction (CD) during generation of the perforation.
12. The method according to claim 10 , wherein the elastic film provided with the perforation is laminated with at least one cover layer of nonwoven.
13. The method according to claim 12 , wherein the elastic film and the at least one cover layer of nonwoven are connected to one another at connection surfaces or connection points by ultrasonic welding.
14. The method according to claim 12 , wherein the elastic film expands to an expanded state along the preferred expansion direction after the perforation is generated and is connected to the at least one cover layer of nonwoven in the expanded state.