| abstract |
Provided is a surface crosslinking method for producing a water-absorbing agent having excellent physical properties such as water-absorbing performance. A surface cross-linking method for a water-absorbing resin, the method comprising at least a surface cross-linking agent addition step and a heat treatment step, wherein the water-absorbing resin used in the surface cross-linking agent addition step has a water content of 40 mass. The surface cross-linking agent addition step is a step in which the water-absorbent resin and the surface cross-linking agent are in contact, the temperature of the water-absorbent resin at the time of contact is 40 ° C. or higher, and the heat treatment step It is a step of heating the surface cross-linking agent-containing water absorbent resin obtained in the surface cross-linking agent addition step to at least 100 ° C., and the minimum temperature until the surface cross-linking agent-containing water absorbent resin reaches 100 ° C. in the heat treatment step Is a method of -10 ° C. or higher based on the temperature of the water absorbent resin when the surface cross-linking agent and the water absorbent resin are in contact with each other. [Selection figure] None |