Methods and apparatuses for assembling elastic laminates with different bond densities for absorbent articles
The methods herein relate to assembling an elastic laminate with a first elastic material and a second elastic material bonded between first and second substrates. During assembly, an elastic laminate may be formed by positioning the first and second substrates in contact with stretched central regions of the first and second elastic materials. The elastic laminates may include two or more bonding regions that may be defined by the various layers or components of the elastic laminate that are laminated or stacked relative to each other. In some configurations, a first plurality of ultrasonic bonds are applied to the elastic laminate to define a first bond density in the first bonding region, and a second plurality of ultrasonic bonds are applied to the elastic laminate to define a second bond density in the second bonding region, wherein the second bond density is not equal to the first bond density.
1. A method for assembling elastic laminates, the method comprising steps of:
providing a first substrate and a second substrate, the first substrate and the second substrate each comprising a first surface and an opposing second surface, a first longitudinal edge and a second longitudinal edge separated from the first longitudinal edge to define a width in a cross direction;
providing a first elastic film and a second elastic film, each of the first elastic film and the second elastic film comprising a stretched central region;
positioning the stretched central region of the first elastic film in contact with the second surface of the first substrate;
positioning the stretched central region of the second elastic film in contact with the second surface of the first substrate;
forming an elastic laminate by advancing the second substrate in a machine direction to position the first surface of the second substrate in contact with the stretched central regions of the first and second elastic films, wherein the elastic laminate comprises a first bonding region and a second bonding region, wherein the first bonding region is defined where the stretched central region of the first elastic film is in direct contact with the second surface of the first substrate and the first surface of the second substrate, and wherein the second bonding region is positioned completely outside the first bonding region;
applying a first plurality of ultrasonic bonds to the elastic laminate to define a first bond density in the first bonding region; and
applying a second plurality of ultrasonic bonds to the elastic laminate to define a second bond density in the second bonding region, wherein the first bond density is not equal to the second bond density and wherein the elastic laminate comprises at least one more layer in the second bonding region than in the first bonding region.
2. The method of claim 1 wherein the at least one more layer comprises a reinforcement layer.
3. The method of claim 1 wherein the at least one more layer comprises a folded portion of the first substrate, wherein the first longitudinal edge of the first substrate is positioned between an edge region of the first elastic material and the second surface of the first substrate.
4. The method of claim 1 further comprising the step of: cutting the elastic laminate along the machine direction between the first elastic film and the second elastic film into a first elastic laminate and a second elastic laminate.
5. The method of claim 4 wherein the step of cutting the elastic laminate further comprises cutting through the second bonding region.
6. The method of claim 1 wherein the second bonding region at least partially overlaps an unstretched edge region of the first elastic film.
7. The method of claim 1 wherein the second bonding region at least partially overlaps an unstretched edge region of the second elastic film.
8. The method of claim 1 , wherein the step of providing a first elastic film and a second elastic film further comprises stretching a central region of the first elastic film in the cross direction and stretching the central region of the second elastic film in the cross direction.
9. The method of claim 1 , further comprising steps of:
stretching a central region of an elastic film in the cross direction;
positioning the stretched central region of the elastic film in contact with the first substrate; and
cutting the stretched central region of the elastic film along the machine direction into the first elastic film and the second elastic film.
10. A method for assembling elastic laminates, the method comprising steps of:
providing a first substrate and a second substrate, the first substrate and the second substrate each comprising a first surface and an opposing second surface, a first longitudinal edge and a second longitudinal edge separated from the first longitudinal edge to define a width in a cross direction;
providing a first elastic film and a second elastic film, each of the first elastic film and the second elastic film comprising a stretched central region;
positioning the stretched central region of the first elastic film in contact with the second surface of the first substrate;
positioning the stretched central region of the second elastic film in contact with the second surface of the first substrate;
forming an elastic laminate by advancing the second substrate in a machine direction to position the first surface of the second substrate in contact with the stretched central regions of the first and second elastic films, wherein the elastic laminate comprises a first bonding region and a second bonding region, wherein the first bonding region is defined where the stretched central region of the first elastic film is in direct contact with the second surface of the first substrate and the first surface of the second substrate, and wherein the second bonding region is positioned completely outside the first bonding region;
applying a first plurality of ultrasonic bonds to the elastic laminate to define a first bond density in the first bonding region; and
applying a second plurality of ultrasonic bonds to the elastic laminate to define a second bond density in the second bonding region, wherein the first bond density is not equal to the second bond density, or wherein the first bond density is equal to the second bond density and wherein at least one of the first plurality of ultrasonic bonds comprises a shape that is different from a shape of at least one of the second plurality of ultrasonic bonds.
11. The method of claim 10 further comprising the step of: cutting the elastic laminate along the machine direction between the first elastic film and the second elastic film into a first elastic laminate and a second elastic laminate.
12. The method of claim 11 , wherein the step of cutting the elastic laminate further comprises cutting through the second bonding region.
13. The method of claim 10 , wherein first bond density is defined by a first bond frequency and the second bond density is defined by a second bond frequency.
14. The method of claim 10 , wherein first bond density is defined by a first aggregate bond coverage and the second bond density is defined by a second aggregate bond coverage.
15. The method of claim 10 , wherein the first bond density is less than the second bond density.
16. The method of claim 10 , wherein the step of forming an elastic laminate further comprises positioning the first substrate in direct contact with the second substrate, and wherein the second bonding region is defined where the first substrate is in direct contact with the second substrate.