Water Absorbing Agent Bulk Density Surfactant

The invention changes the chemical parameter of the resin by introducing a hydrophobic group through reaction with an organic isocyanate compound. This chemical modification alters the surface properties of the resin particles, creating a hydrophobic surface layer that prevents liquid bridging between particles. This allows the resin to maintain higher bulk specific gravity even when specific surface area is increased, as the hydrophobic surface prevents the capillary action that would otherwise cause particles to aggregate and reduce bulk density.

The invention modifies the surface chemical parameters of the resin by adding a hydrophobic group through isocyanate reaction. This creates a protective hydrophobic surface layer that reduces particle-particle adhesion and prevents liquid bridging. As a result, the resin particles maintain their structural integrity during vibration filling, as the hydrophobic surface prevents the formation of liquid bridges that would otherwise cause particle aggregation and mechanical damage during the vibration process.

Instead of adding a separate surfactant substance to modify surface properties, the invention creates a surfactant-like hydrophobic surface layer directly on the resin particles through chemical reaction with isocyanate compounds. This in-situ formed hydrophobic layer copies the function of external surfactants by reducing surface tension and preventing liquid bridging, but without the harmful side effect of decreasing the surface tension of the absorbed liquid. The hydrophobic group is covalently bonded to the resin, ensuring it remains fixed and does not leach into the absorbed liquid.