Apparatus For Applying Fluid To An Intaglio Roll For Transfer To A Soft, Absorbent Fibrous Web

What is this patent about?

'657 is related to the field of applying fluids to fibrous webs, specifically for applying adhesives to soft, absorbent materials like sanitary paper using an intaglio roll. Traditional methods suffer from issues like adhesive deterioration due to air exposure, contamination from loose fibers picked up from the web, and uneven fluid application, especially at high speeds.

The underlying idea behind '657 is to improve the uniformity and cleanliness of adhesive application to an intaglio roll. This is achieved by using a small, unpressurized reservoir to apply the fluid, combined with a pre-wipe blade to ensure the recesses in the intaglio roll are completely filled and to create a uniform, thinner layer of fluid before the final doctor blade removes excess adhesive.

The claims of '657 focus on an apparatus for applying fluid to an intaglio roll, comprising a small, unpressurized reservoir that extends across the width of the roll, a pre-wipe member positioned above the reservoir to distribute fluid and fill recesses, and a doctor blade positioned beyond the pre-wipe member to remove excess fluid, leaving fluid only in the recesses. The reservoir is designed to flow fluid upward with a uniform velocity profile.

In practice, the intaglio roll rotates through the unpressurized reservoir, picking up a layer of adhesive. The pre-wipe blade, set at an acute angle to the roll surface, then forces the fluid into the recesses and creates a thinner, more uniform layer. This reformed layer then passes under the doctor blade, which removes almost all the remaining fluid from the surface, leaving adhesive only in the desired pattern. The overflow from the reservoir is continuously recirculated and filtered to remove fibers.

This design differs from prior approaches by using a combination of an unpressurized reservoir and a pre-wipe blade. The unpressurized reservoir minimizes air exposure and allows for continuous flushing of fibers. The flexible pre-wipe blade, positioned at a specific angle, ensures complete filling of the intaglio recesses and creates a uniform fluid layer, reducing the load on the doctor blade and minimizing wear on the intaglio roll. The uniform flow velocity profile across the reservoir width is achieved by flowing the fluid against an impingement member before it enters the reservoir.