Thermo-mechanical modification of nonwoven webs
OwnerGregory F. Wardinventor
Life of this patent
Estimating the term…
Abstract
Heat bonded thermoplastic and partially thermoplastic nonwoven webs which have been thermomechanically treated while under low strain rate tension show significant improvement to their coformability and softness. More importantly the low strain rate thermomechanical treatment imparts a high degree of commercially valuable elasticity. The resultant webs find use in all nonwoven applications where softness, conformability and elasticity are useful. The resultant webs develop elasticity in only one direction but the two embodiments provide the ability to create elasticity in the machine or cross machine direction of a roll of precursor material. In addition virtually any precursor web containing at least 70% thermally bonded thermoplastic fibers can be used.
Claims9
A nonwoven web having elastic properties in the cross-machine direction wherein the anisotropic precursor web consists essentially of thermally bonded thermoplastic and non-thermoplastic fibers, said nonwoven web containing from 60 to 100% thermoplastic fibers and the remainder non-thermoplastic fibers, said precursor web being continuously drawn within a web heating means by a multiplicity of drawing means wherein the heated web is subjected to a variable tension means sufficient to provide a strain rate of at least 3.5 in./in./minute but equal to or less than 8 in./in./minute, said strain rate calculated based on the apparent gage length between individual elements of said tension means, whereby the resultant web is characterized by a narrowing of its lateral dimension, an increase in its length, an increase in web thickness and the development of a web elasticity of at least 85% recovery after being elongated at least 50% in the direction perpendicular to and in the same plane as the drawing forces.
A nonwoven web having elastic properties in the machine direction wherein the anisotropic precursor web consists essentially of thermally bonded thermoplastic and nonthermoplastic fibers, said nonwoven web containing from 60 to 100% thermoplastic fibers and the remainder nonthermoplastic fibers, said precursor web being continuously drawn within a web heating means by a multiplicity of drawing means wherein the heated web is subjected to a variable tension means sufficient to provide a strain rate of at least 3.5 in./in./minute but equal to or less than 8 in./in./minute, said strain rate calculated based on the apparent gage length between individual elements of said tension means, whereby the resultant web is characterized by a reduction of its length dimension, an increase in its lateral dimension, an increase in web thickness and the development of a web elasticity of at least 85% recovery after being elongated at least 50% in the direction perpendicular to and in the same plane as the drawing forces.
Dependencies are inferred from the claim text.