Elastic nonwoven sheet
View Patent ↗This invention relates to stretchable nonwoven sheets prepared by substantially uniformly impregnating a necked nonwoven substrate with an elastomeric polymer by treatment with an elastomeric polymer solution. The nonwoven sheet is useful in the manufacture of diapers and other hygiene articles.
1. A method for forming a stretchable nonwoven sheet comprising the steps of:
providing a necked nonwoven substrate having a thickness, first and second outer surfaces, a machine direction and a cross-direction, the necked nonwoven substrate having an percent elongation of at least 30% in the cross-direction;
substantially uniformly impregnating the necked nonwoven substrate with a solution comprising an elastomeric polymer dissolved in a solvent; and
removing the solvent from the impregnated nonwoven substrate by wet coagulation to deposit the elastomeric polymer substantially uniformly throughout the thickness of the nonwoven substrate without forming a substantially continuous layer of elastomeric polymer on either of the first or second outer surfaces of the nonwoven substrate.
2. The method according to claim 1 wherein the necked nonwoven substrate has a percent elongation of less than about 5% in the machine direction and a percent elongation in the cross-direction of between about 100% and about 300%.
3. The method according to claim 1 wherein the necked nonwoven substrate is a necked nonwoven fabric having a basis weight between about 15 g/m 2 and about 70 g/m 2 .
4. The method according to claim 1 wherein the elastomeric polymer is a polyurethane.
5. The method according to claim 1 wherein the elastomeric polymer is deposited on the substrate at about 15 to 55 weight percent based on the combined weight of the substrate and the elastomeric polymer.
6. The method according to claim 1 further comprising a step of sanding or napping at least one of the outer surfaces of the nonwoven sheet after the solvent has been removed to raise fibers on the surface of the sheet.