Patent ID: 8420567

Claim:
A process to make a particulate superabsorbent polymer composition having increased permeability comprising the steps of a) preparing a neutralized monomer solution comprising a polymerizable monomer selected from unsaturated acid groups-containing monomers, ethylenically unsaturated carboxylic acid anhydride, salts, or derivatives thereof and a caustic agent selection from an alkali agent, wherein the polymerizable monomer is neutralized to from about 50 mol % to about 85 mol %; b) forming a crosslinker monomer mixture by adding an internal crosslinker composition to the neutralized monomer solution wherein the internal crosslinker composition is the reaction product of amines and glycidyl compounds selected from, (i) saturated amines and/or saturated polyamines with ethylenically unsaturated glycidyl and/or ethylenically unsaturated polyglycidyl compounds, or (ii) ethylenically unsaturated amines and/or ethylenically unsaturated polyamines with saturated glycidyl compounds and/or saturated polyglycidyl compounds, or (iii) ethylenically unsaturated amines and/or ethylenically unsaturated polyamines with ethylenically unsaturated glycidyl compounds and/or ethylenically unsaturated polyglycidyl compounds; wherein the amount of the amines and glycidyl compounds includes a stoichiometric excess of amines/unreacted amino functions wherein the amount of the glycidyl groups is from 75% to 98% of the molar amount of the NH-functions, and the internal crosslinker composition has a residual amount of glycidyl compounds of less than about 500 ppm based on the mass of the internal crosslinker composition as determined by the Glycidyl Compound in Amine-Glycidyl Compound Reaction Products Test set forth herein; c) polymerizing the crosslinker monomer mixture to make a superabsorbent polymer wherein components a) and b) are polymerized; d) granulating the superabsorbent polymer of step c) to form superabsorbent polymer particles having a surface and wherein at least about 40 wt % of the superabsorbent polymer particles have a size of from about 150 μm to about 850 μms; and e) surface treating the particulate superabsorbent polymer with from about 0.01 to about 5 wt % based on a dry particulate superabsorbent polymer composition weight of surface crosslinking agent applied to the particle surface; wherein the particulate superabsorbent polymer composition has a Centrifuge Retention Capacity of from about 20 g/g to about 40 g/g as determined by the Centrifuge Retention Capacity Test set forth herein, and a Gel Bed Permeability of at least about 5 Darcy or more as determined by the Free-Swell Gel Bed Permeability Test set forth herein.