Sticking to Press Rolls

Eucalypt woods do not contain resinous extractives, but adhesion of kraft eucalypt pulps to the press can occur, and this has been overcome by overcooking the wood. The problem can be prevented more cheaply by adding dilute solutions of sodium hexametaphosphate to the press roll or some other compounds that would form sparingly dissociated compounds with iron and aluminum ions (48). 

The tropical species Dillenia pulchella and Tetramerista glabra produce very sticky pulps that are difficult to remove from the laboratory sheet machine (92, 93). 

The recycling of the process water from a hardboard mill utilizing hardwoods has resulted in sticking of the boards at the press (36). In some cases the cause may be the thin layer of hemicelluloses, which under wet conditions and with heat from the rolls have passed the glass transition point to become plastic so that the paper web from semichemical pulps sticks to the rolls. The addition of a mixture of solvents, dispersants, and emulsifiers to NSSC pulps can control deposit formation at the wet end of the machine (56). 

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