Superabsorbent resin (SAP for short) is a water-swelling macromolecule polymer containing strong hydrophilic groups such as spindle group and with a certain degree of cross-linking. It has a strong water-absorbing property and water-retaining ability.The amount of water absorption of superabsorbent resin, can reach hundreds of times of its own mass, water absorption speed is fast, and water retention is strong, even under the condition of heat, pressure is not easy to lose water.SAP is widely used in personal care products such as disposable diapers, adult incontinence products and women's hygiene products due to its good water absorption, moderate price and good safety performance.

Superabsorbent resin is a network of three dimensional crosslinking polymeric chains. Its water absorption is formed by weak chemical bonds.Superabsorbent resin is a kind of high polymer electrolyte. The interaction between ions produced after ionization in water causes the resin to swell.Moreover, with the increase of the concentration of ions inside the resin, the difference of concentration between the resin and the outside solution will result in reverse osmosis, making water enter the resin further.How much SAP absorbs water depends on the osmotic pressure between the polymer electrolyte and the water until the osmotic pressure and the elasticity of the polymer network reach a balance.