Oxidised Tapioca Starch (Paper & Corrugating Grade)

About This Product

Paper mills and corrugators are among the largest industrial users of starch, and almost all of it is oxidised. The reason is a viscosity problem. A size press or a glue machine has to apply a controlled, thin, even film at speed, which means the starch liquor must carry a high solids content at a low viscosity. Native starch does the opposite: it reaches an unpumpable viscosity at a solids level far below what the process needs. Controlled hypochlorite oxidation solves it by cleaving the chains. Viscosity falls sharply, so the liquor can be run at thirty per cent solids and above, and it stays stable rather than setting back in the tank as it cools. At the same time oxidation converts hydroxyl groups to carboxyl, which are anionic and bond strongly to cellulose fibre. The practical effect on paper is higher surface strength and better pick resistance in offset printing, reduced linting, improved stiffness, and a sealed surface that cuts ink demand. In corrugating the same properties are used differently. In a Stein-Hall adhesive the starch is split between a cooked carrier fraction and a raw suspended fraction, with caustic and borax controlling the gelatinisation point. The adhesive must stay fluid until the flute tip meets the liner and then gel almost instantly against the hot plate. Oxidised tapioca gives a fast, sharply defined gel point and a high green bond, which is what allows corrugator speed to be raised without green-bond failure or warp. Tapioca is preferred over maize in some mills for its low protein and lipid content, which means less foam in the size press and no rancid odour in stored liquor, and for its lower gelatinisation temperature, which reduces cooking steam. It is also used as a binder in paper coating colour, as a retention and strength aid, and in gypsum wallboard adhesive. Bio Green Chem supplies paper and corrugating grade oxidised tapioca starch in 25 kg bags and jumbo bags. Carboxyl content, viscosity at working solids, gel point, whiteness and ash are confirmed on the agreed specification and on the batch certificate of analysis.