Method for applying binding agents to fibrous webs
AssigneeJames River-Dixie/Northern, Inc.
InventorsWalter L. Pauls, Raymond A. Dunleavy, III
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Abstract
A method and system for applying a foamed binding agent to a fibrous web is disclosed. The invention is characterized by the use of an extruder having an upper lip extending 1/16 to 1/4 inch beyond the lower lip, and by the drawing of a vacuum beneath the applied foam, said characteristics being critical to the formation of a uniform foam layer atop the web. A second, more substantial vacuum is then applied beneath the web to essentially completely draw the binding agent into the web thereby providing substantial inter-fiber bonding.
Claims21
A method of applying binding agent onto a second side of a fibrous web whose first side had been bonded previously, the method comprising the steps of:
- (a) providing said once bonded fibrous web on a moving foraminous carrier, second side facing up,
- (b) applying to said second side a foamed dispersion of a binding agent by extruder means, the extruder being characterized by an orifice outlet whose upper lip extends beyond its lower lip by between 1/16 and 1/4 inch, said foamed dispersion being applied at an exit velocity approximately equal to the carrier velocity,
- (c) drawing beneath said foraminous carrier a first vacuum just downstream of the extruder outlet orifice, said vacuum being between about 0.10 to 1.0 inch of water, whereby the foamed dispersion remains uniformly atop the web, the
- (d) drawing beneath the carrier a second vacuum further downstream of the extruder means, said vacuum being about between 2 and 15 inches of mercury, whereby the foamed dispersion is caused to penetrate said web.
A method of applying binding agent to each side of a loose fibrous web, the method comprising the steps of:
- (a) providing said fibrous web on a first moving foraminous carrier, first side facing up,
- (b) applying to said first side a binding agent emulsion,
- (c) at least partially drying said once bonded web,
- (d) transferring said web to a second moving foraminous carrier, the web being inverted thereby,
- (e) applying to said second side a foamed dispersion of a binding agent by extruder means, the extruder characterized by an orifice outlet whose upper lip extends beyond its lower lip by between 1/16 and 1/4 inch, said foamed dispersion being applied at an exit velocity approximately equal to the carrier velocity,
- (f) drawing beneath said foraminous carrier a first vacuum just downstream of the extruder outlet orifice, said vacuum being between about 0.10 to 1.0 inch of water, whereby the foamed dispersion remains uniformly atop the web, and
- (g) drawing beneath the carrier a second vacuum further downstream of the extruder means, said vacuum being about between 2 and 15 inches of mercury, whereby the foamed dispersion is caused to penetrate said web.
Dependencies are inferred from the claim text.