Minnesota Mining and Manufacturing Company

Harvey J Berg

James F Dyrud

Joseph P Kronzer

Alice C Murray

Roger J Stumo

A method of forming a cup-shaped, non-woven fibrous shaping layer for a filtering face mask. The method includes the steps: (a) heating a non-woven fibrous web that contains at least 40 weight percent thermally bonding fibers, where at least 10 weight percent of the fibrous material is bicomponent fibers, to a temperature at which the thermally bonding fibers, including at least one component of the bicomponent fibers, are softened; and then (b) molding the heated non-woven fibrous web, while the thermally bonding fibers and the at least cone component of the bicomponent fibers are still soft, in a mold having molding members that are at a temperature below the softening temperatures of the thermally bonding fibers, including all components of the bicomponent fibers.

Methods of forming fibrous filtration face masks

New molded fibrous filtration face masks that are highly resilient and shape-retaining are provided using one or more molded fibrous shaping layers, with a fibrous filtration layer disposed on one side of or between the molded fibrous shaping layers; the molded fibrous shaping layers having a total basis weight of at least 150 g/m2, and at least one of the fibrous shaping layers having an average density over the central area of the face mask of no greater than about 0.2 g/cc, such that at bends of the layer during deformation of the face mask the layer elastically deforms and tends to return to its original thickness and shape when the deforming pressure is removed.

Resilient shape-retaining fibrous filtration face mask

Molded filtration products, such as disposable face masks, are prepared by assembling at least one fibrous shaping layer and one fibrous filtration layer in face-to-face contact and subjecting the assembly to heat and molding pressure. Preferably the assembly comprises two shaping layers, one on each side of the filtration layer. The shaping layers in total weight no more than about 150 pounds per ream and contribute no more than about 20 percent of the total pressure drop through the filtration product. At least one of the shaping layers comprises fibers that can be bound together at points of fiber intersections by coalescence of binder material on the fibers.

Growing community of inventors

Saint Paul, MN, United States of America

Harvey J Berg