Back to results
US 2017/0361254 A1Published application
Melt spun filtration media for respiratory devices and face masks
AssigneeE. I. Du Pont de Nemours and Company
InventorsTao Huang, Neil Jay Croft, Jr., Zachary R. Dilworth
Life of this patent
Estimating the term…
Abstract
The present disclosure is directed toward an improved nanofibrous electret filtration media of which the stand-alone electret nanofibrous web comprises a single source randomly intermingled fiber network that yields high breathability due to the high porosity and improved filtration efficiency for use as improved filtration media for respiratory devices and face masks.
Claims21
A nanofibrous web comprising polymeric fibers that are intimately comingled and entangled in a single layer, stand-alone network, and wherein:
- (a) the fibers comprise at least 70% nanofibers, 5%-25% microfibers, and 0%-5% coarse fibers by number percentage;
- (b) a number average diameter of all the fibers is less than 1000 nm and a median diameter of all the fibers is less than 500 nm;
- and
- (c) the nanofibrous web has an apparent density of 0.01 to 0.05 g/cm3, an electrostatic charge of at least 12 kV as measured at a distance of 25 mm, and an effective quality factor (eQF) of greater than about 2.5 (Pa·g/cm3)−1.
1 more element
A process for producing a nanofibrous web, comprising:
- (i) supplying a molten polymeric spinning melt to a surface of a rotating member having a discharge edge;
- (ii) rotating the rotating member at a rotational speed sufficient to form a film of the melt on the member, the film having an instability characterized by a wavy, non-uniform film thickness having regions of undulating thickness that extend radially outward from the center of the rotating member to its edge;
- (iii) discharging from the discharge edge a plurality of discrete, continuous filaments derived from the film melt into a stretching zone;
- (iv) attenuating the discharged discrete filaments in the stretching zone by centrifugal force to form continuous fibers;
- (v) electrostatically charging the filaments in the stretching zone;
- and
- (vi) collecting the attenuated continuous fibers on a collection surface to form the nanofibrous web as a single layer, stand-alone network,
- and wherein the fibers comprise at least 70% nanofibers, 5%-25% microfibers, and 0%-5% coarse fibers by number percentage, and a number average diameter of all the fibers is less than 1000 nm and a median diameter of all the fibers is less than 500 nm.
5 more elements
Dependencies are inferred from the claim text.