b'maintaining roll size and density: Reduced fiber cost per case4.Increase creping moisture while maintaining bulk: Reduced energy consumption 5.Substitute with lower quality fiber while maintaining bulk: Reduced fiber costLeverage marketing opportunities:1.Promote the absorbency gain vs competition obtained via reduced sheet density2.Wind larger roll size to benefit from the customer perception of value on the shelfDesign of the base sheet parameters and efficient execution ofFigure 1. Yankee coating film tack vs wet web moisture.manufacturing is critical to separating the wheat from the chaff. Those whoadhesive is being used. As an example,As such, most cellulosic structures do so will enjoy better product qualitythe graph above displays the tackexhibit their maximum strength and operational efficiency. curves of several commonly usedproperties somewhere between 6 and creping adhesives vs creping moisture10% moisture. As the paper is dried ADJUSTING THE CREPING FOR BULK and temperature. below this level, the sheet becomes CREPING MOISTURE: more brittle and strength properties The adjustment of the creping moistureAs we can see, many commonare reduced. The result is that as to impact bulk is a commonly usedadhesives are losing tack as crepingwe reduce creping moisture, we are method. The basic understoodmoisture is driven down due to thebringing a weaker sheet to the face principle is that adhesion increasesglass transition profile or reducedof the blade, which will result in more as creping moisture reduces.It isinternal bond strength as water contentsheet explosion at similar speeds and accepted that this increased adhesionis driven out of the polymer matrix.adhesion levels.will result in the generation of more bulk. Empirically, the premise oftenAnother basic premise driving anIn order to maximize bulk generation, plays out this way, but more is at playIn order toincrease in bulk at lower crepingthe correct adhesive package must here. maximize bulkmoistures relates to the inherentbe chosen for the intended creping generation,properties of hydrogen bondingmoisture range. This is particularly true Some creping chemistries will indeedthe correctof cellulose fibers. The primaryat the extremes of the LDC creping become harder, resulting in a greateradhesivebonding mechanism between fibersmoisture range, below 3% or above adhesion of the sheet to the Yankee,package mustin paper is due to hydrogen bonding.6%. Signs that your adhesive package as creping moisture is reduced. Thisbe chosen forThis hydrogen bonding potential isis unsuited to your conditions would be:in not, however, a universal fact andthe intendedmaximized via a small amount ofUnstable sheet handlingis highly dependent on where in thecrepingbound water within the paper structureBreaks, pick-outssurface temperature spectrum you aremoistureby several mechanisms includingReducing moisture results in beginning and what type of crepingrange.plasticizing of the fibers and bridging. lower, not higher bulk TISSUE TECHNOLOGY INTERNATIONAL23'