Foam-assisted application of uncooked starch and dry strength agents to paper products

A method for manufacturing a multi-ply paperboard product, the method comprising:

• forming a base embryonic ply web by discharging a first aqueous paper stock from a first headbox onto a moving first forming fabric, the first aqueous paper stock comprising pulp fibers, wherein water drains through the first forming fabric to increase the consistency of the first paper stock to form the base embryonic ply web, the base embryonic ply web having a first surface and an opposite second surface;
• dewatering the base embryonic ply web to a consistency of from 6 to 12% dry solids;
• generating a foam comprising water, air, a foaming agent, uncooked starch particles having a mean maximum dimension of from 5 to 50 microns, and dissolved molecules of a dry strength agent;
• applying the foam to the first surface of the base embryonic ply web while the base embryonic ply web is carried on the first forming fabric;
• applying vacuum pressure to the second surface of the base embryonic ply web to draw the foam into the base embryonic ply web, wherein the vacuum pressure physically retains the uncooked starch particles by filtration at or near the first surface while drawing the dissolved molecules of the dry strength agent into the base embryonic ply web to a greater depth than the retained uncooked starch particles;
• forming an applied embryonic ply web on a second forming fabric by discharging a second aqueous paper stock from a second headbox;
• combining the base embryonic ply web with the applied embryonic ply web at a combining roll to form a combined ply web, wherein the first surface of the base embryonic ply web contacts a surface of the applied embryonic ply web at an interface;
• and
• drying the combined ply web under conditions of sufficient moisture, temperature, and time to gelatinize the uncooked starch particles retained at the interface and form an adhesive ply bond between the base embryonic ply web and the applied embryonic ply web.