Patent ID: 8596931
Filing Date: 2013-12-03
Classification: A61L,B01J,C08J

Abstract:
1. A method for producing a particulate water absorbing agent including (i) a water absorbent resin having been subjected to a surface cross-linking treatment with use of an organic surface cross-linking agent and (ii) a liquid permeability improving agent, the method comprising the steps of: (a) providing a water absorbent resin by cross-linking and polymerizing an unsaturated monomer containing an acid group and/or its salt; (b) after the step (a), forming a surface cross-linked layer on the water absorbent resin by adding an organic surface cross-linking agent to the water absorbent resin having a cross-linked structure; (c) forming a liquid permeability improving agent layer on the water absorbent resin by adding a liquid permeability improving agent to the water absorbent resin concurrently with or after the step of adding the organic surface cross-linking agent; (d) forming a lubrication improving agent layer on the water absorbent resin by adding a lubrication improving agent to the water absorbent resin concurrently with or after the step of adding the liquid permeability improving agent; and (e) pneumatically transporting a particulate water absorbing agent with use of a low-density pneumatic transportation device or a high-density pneumatic transportation device, the particulate water absorbing agent being obtained by carrying out the steps (b), (c) and (d).