Bath tissue paper softening method and apparatus

Abstract

An apparatus and method for manufacturing bath tissue paper utilizing at least one through-air dryer in which a softening agent is applied to a paper web before the paper web is sent through at least one through-air dryer. A slurry is deposited between two forming wires. Then, at a first web transfer device, the outer forming wire is removed from the paper web, with the paper web remaining on the inner forming wire. At a second web transfer device, the paper web is separated from the inner forming wire and is pulled onto a TAD fabric by use of suction. Then a softening agent is applied to the paper web before the paper web is sent through at least one through-air dryer.

What is claimed is: 
     
         1 . A method comprising:
 forming a paper web by depositing, by a pressurized headbox, a slurry between a first forming wire and a second forming wire;   transporting the paper web to a first web transfer device;   separating, by the first web transfer device, the paper web from the first forming wire and retaining the paper web on the second forming wire;   transporting the paper web to a second web transfer device;   separating, by the second web transfer device, the paper web from the second forming wire by pulling the paper web onto a through-air dryer fabric (TAD fabric);   transporting the paper web to a spray applicator;   spraying, by the spray applicator, a softening agent on one surface of the paper web;   transporting the paper web through at least one through-air dryer (TAD), the at least one TAD including a rotatable porous cylinder and a hood; and   at least partially drying the paper web by wrapping the TAD fabric and the paper web about a portion of the rotatable porous cylinder while blowing air through the rotatable porous cylinder, the paper web, and the TAD fabric, wherein the drying comprises removal of water and solvents.   
     
     
         2 . The method of  claim 1 , further comprising partially dewatering the paper web before transporting the paper web to the second web transfer device. 
     
     
         3 . The method of  claim 1 , further comprising partially dewatering the paper web after the paper web exits the second web transfer device and before the paper web reaches the spray applicator. 
     
     
         4 . The method of  claim 1 , further comprising, after the paper web exits the at least one through-air dryer, transporting the paper web on the through-air dryer fabric to a second type of dryer to further dry the paper web. 
     
     
         5 . The method of  claim 4 , wherein the second type of dryer is a yankee dryer. 
     
     
         6 . The method of  claim 3 , further comprising, upon exiting the second type of dryer, creping the paper web with a blade, wherein the creping creates a plurality of microfolds in the paper web. 
     
     
         7 . The method of  claim 1 , further comprising, after spraying the softening agent on the one surface of the paper web, transporting the through-air dryer fabric (TAD fabric) and the paper web through at least one additional through-air dryer (TAD), the at least one additional TAD disposed after a first TAD. 
     
     
         8 . The method of  claim 1 , wherein the at least one through-air dryer is configured in an inward flow arrangement wherein drying air is flowed from the hood through the paper web and the through-air dryer fabric, and into the interior of the rotatable porous cylinder. 
     
     
         9 . The method of  claim 1 , wherein the at least one through-air dryer is configured in an outward flow arrangement wherein drying air is flowed from the interior of the rotatable porous cylinder, through the paper web and the through-air dryer fabric, and out to the hood. 
     
     
         10 . An apparatus comprising:
 an outer forming wire and an inner forming wire between which a slurry is deposited to form a paper web;   a first web transfer device that separates the paper web from the outer forming wire and retains the paper web on the inner forming wire;   a second web transfer device that separates the paper web from the inner forming wire by pulling the paper web onto a through-air dryer fabric (TAD fabric);   a spray applicator that sprays a softening agent onto at least one surface of the paper web while the paper web is retained on the TAD fabric; and   at least one through-air dryer (TAD), comprising at least one rotatable porous cylinder and a hood, wherein the at least one TAD at least partially dries the paper web by wrapping the TAD fabric and the paper web about a portion of the rotatable porous cylinder while blowing air through the rotatable porous cylinder, the paper web, and the TAD fabric.   
     
     
         11 . The apparatus of  claim 10 , further comprising a vacuum dewatering device disposed between the first web transfer device and the second web transfer device that partially dewaters the paper web while the paper web is retained on the inner forming wire. 
     
     
         12 . The apparatus of  claim 10 , further comprising a vacuum dewatering device disposed between the second web transfer device and the spray applicator that partially dewaters the paper web while the paper web is retained on the TAD fabric. 
     
     
         13 . The apparatus of  claim 10 , further comprising a second type of dryer to further dry the paper web, the second type of dryer located subsequent to the at least one through-air dryer. 
     
     
         14 . The apparatus of  claim 13 , wherein the second type of dryer is a yankee dryer. 
     
     
         15 . The apparatus of  claim 10 , comprising at least two through-air dryers such that the paper web is transported on the through-air dryer fabric (TAD fabric) through a first through-air dryer (TAD) and through at least one additional through-air dryer, the at least one additional TAD placed immediately after the first TAD. 
     
     
         16 . The apparatus of  claim 15 , wherein the spray applicator is disposed between the first TAD and an additional TAD, the softening agent being applied after the paper web exits the first TAD and before the paper web enters the additional TAD. 
     
     
         17 . The apparatus of  claim 10 , further comprising a blade disposed after the second type of dryer, the blade creping the paper web, wherein creping the paper web creates a plurality of microfolds in the paper web. 
     
     
         18 . The apparatus of  claim 10 , wherein the at least one through-air dryer is configured in an inward flow arrangement wherein the air is flowed from the hood through the paper web and the through-air dryer fabric, and into the interior of the rotatable porous cylinder. 
     
     
         19 . The apparatus of  claim 10 , wherein the at least one through-air dryer is configured in an outward flow arrangement wherein the air is flowed from the interior of the rotatable porous cylinder, through the paper web and the through-air dryer fabric, and out to the hood. 
     
     
         20 . A method comprising:
 forming a paper web by depositing, by a pressurized headbox, a slurry between a first forming wire and a second forming wire;   transporting the paper web to a first web transfer device;   separating, by the first web transfer device, the paper web from the first forming wire, the first web transfer device configured to retain the paper web on the second forming wire;   transporting the paper web to a second web transfer device;   separating, by the second web transfer device, the paper web from the first forming wire by pulling the paper web onto a through-air dryer fabric (TAD fabric);   transporting the paper web through a first through-air dryer (TAD), the first TAD including a rotatable porous cylinder and a hood;   transporting the paper web to a spray applicator;   spraying, by the spray applicator, a softening agent on one surface of the paper web;   transporting the paper web through a second TAD; and   at least partially drying the paper web by wrapping the TAD fabric and the paper web about a portion of the rotatable porous cylinder while blowing air through the porous cylinder, the paper web, and the TAD fabric, wherein drying comprising removal of water and solvents.