Methods and apparatuses for making elastomeric laminates with elastic strands provided with a spin finish
The present disclosure relates to methods for making elastomeric laminates that may be used as components of absorbent articles. The elastomeric laminates may include a first substrate, a second substrate, and an elastic material located between the first and second substrates. During assembly of an elastomeric laminate, a beam is rotated to unwind the elastic strands from the beam, wherein the strands may include a spin finish. First bonds are applied to bond discrete lengths of the stretched elastic strands with and between the first substrate and the second substrate, wherein the discrete first bonds are arranged intermittently along the machine direction. In addition, second bonds are applied between consecutive first bonds to bond the first and second substrates directly to each other, wherein the second bonds extend in the machine direction and may be separated from each other in a cross direction by at least one elastic strand.
1 . A method for making an elastomeric laminate, the method comprising steps of:
providing elastic strands comprising a decitex less than about 300, wherein a first elastic strand is supplied at a first tension and a second elastic strand is supplied at a second tension, wherein the first tension is not equal to the second tension;
advancing the elastic strands in a machine direction;
separating some of the elastic strands from each other by about 0.5 mm to about 4 mm in a cross direction;
stretching the elastic strands, wherein the first elastic strand is stretched to a first elongation and the second elastic strand is stretched to a second elongation, wherein the first elongation is greater than the second elongation;
applying adhesive to at least one of a first substrate and a second substrate;
bonding discrete lengths of the stretched elastic strands between the first substrate and the second substrate with discrete first bonds arranged intermittently along the machine direction, wherein the first bonds comprise adhesive comprising a first basis weight; and
bonding the first substrate and the second substrate directly to each other with second bonds extending in the machine direction between consecutive first bonds, and wherein the second bonds comprise adhesive having a second basis weight, wherein the second basis weight is less than the first basis weight.
2 . The method of claim 1 , wherein the first basis weight is from about 10 gsm to about 50 gsm.
3 . The method of claim 2 , wherein the second basis weight is from about 0.5 gsm to about 10 gsm.
4 . The method of claim 1 , further comprising a step of applying mechanical bonds to the combined first substrate, second substrate, and elastic strands.
5 . The method of claim 4 , wherein the mechanical bonds comprise ultrasonic bonds.
6 . The method of claim 4 , wherein the mechanical bonds comprise heat or pressure bonds.
7 . The method of claim 1 , wherein the step of stretching the elastic strands further comprises changing first cross sectional areas of the elastic strands in an unstretched state to second cross sectional areas of the elastic strands in a stretched state, wherein the second cross sectional areas are less than the first cross sectional areas; and further comprising a step of immobilizing portions of the elastic strands between at least two second bonds by releasing tension from the stretched elastic strands to increase cross sectional areas of the elastic strands from the second cross sectional areas to third cross sectional areas.
8 . The method of claim 1 , further comprising a step of unwinding the elastic strands from beams.
9 . The method of claim 8 , wherein at least one beam comprises two side plates connected with opposing end portions of a mandrel core.
10 . The method of claim 9 , further comprising a step of unwinding at least one elastic strand from the mandrel core.
11 . The method of claim 8 , further comprising steps of:
unwinding the first elastic strand from a first beam at a first speed;
unwinding the second elastic strand from a second beam at a second speed, wherein first speed is not equal to the second speed.
12 . The method of claim 11 , further comprising steps of:
advancing the first substrate and the second substrate in the machine direction at a third speed, wherein the third speed is greater than the first speed and the second speed.
13 . The method of claim 1 , wherein the first substrate and the second substrate comprise nonwovens.
14 . The method of claim 1 , wherein the first bonds correspond with side seams of a diaper pant.
15 . The method of claim 1 , wherein the decitex is less than about 50.