Solutions for super absorbent polymers (SAP)

SAP is a water-soluble plastic with a very high absorption capacity. Specialists refer to it as polyacrylate. Thanks to its enormous swelling capacity, a single gram of SAP can absorb up to 1000 grams of water. A baby diaper requires about 13 grams of SAP, while five grams of this polymer suffice for a woman’s sanitary napkin.

First produced by a melt polymerization process, the plastic requires costly additional processing before it attains suitable quality and form for consumer products. The main SAP process operations are drying, cooling, crushing, dry grinding, sifting, mixing (cross-linking), storing, conveying, and bagging. The Bühler range of supply includes all the core processes and all the mechanical engineering expertise required to completely process SAP material after polymerization.

The main area of application for SAP is various sanitary products: diapers for babies and sanitary napkins for incontinence and feminine hygiene. The properties of SAP are also used for the reverse function of that in diapers, namely to dispense water, such as in flower pots and agriculture. In addition, this polymer is used in water purification systems as a flocculant.


In the early 1960s, the United States Department of Agriculture (USDA) was conducting work on materials to improve water conservation in soils. They developed a resin based on acrylonitrile polymer with an absorption capacity greater than 400 times its weight. Until the 1980s, water absorbing materials were cellulose or fiber-based products with, at most, an absorption capacity of about 20 times their weight. Today's polyacrylate/polyacrylamide copolymers have an absorption capacity greater than 1,000 times their weight.


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