| 摘要 |
PURPOSE:To obtain a water-absorptive resin which can absorb pure water and an aqueous electrolyte solution at a high absorption speed and has an ability to diffuse them by sulfonating a polystyrene foam to its inside. CONSTITUTION:A polystyrene foam is sulfonated with at least one member selected from among fuming sulfuric acid, chloro or fluoro-sulfonic acid and sulfur trioxide, and the product is optionally converted into a salt. As the polystyrene, a homopolymer or a copolymer with butadiene or acrylonitrile can be used and it is desirable that it has a comonomer content above 40mol%. As the polystyrene foam, a waste of a heat-insulation material or a cushioning material can be used. As the fuming sulfuric acid, commercially available 20-30% fuming sulfuric acid can be used as such. The sulfonation is usually carried out at 90-100 deg.C for about 3-8hr. The sulfur content of the product is about 16-21% for all of these sulfonating agents and can reach such a degree as to be sulfonated to the inside or near. As the neutralizing agent, an alkali is usually used. |
