Particulate superabsorbent polymer composition having improved performance properties

A particulate superabsorbent polymer composition comprising a polymer comprising:

• a) from about 55 wt % to about 99.9 wt % of polymerizable unsaturated acid group containing monomers;
• b) from 0 wt % to 40 wt % of polymerized, ethylenically unsaturated monomers copolymerizable with a);
• c) from about 0.001 wt % to about 5.0 wt % based on the weight of a) of an internal crosslinking agent, wherein the components a), b) and c) are polymerized into a hydrogel which is granulated into particulate superabsorbent polymer having a surface;
• d) from about 0.001 wt % to about 5.0 wt % based on the dry particulate superabsorbent composition weight of surface crosslinking agent applied to the surface of the particulate superabsorbent polymer;
• and
• e) from about 0.01 wt % to about 5 wt % based on the dry particulate superabsorbent composition weight of aluminum salt applied to the surface of the particulate superabsorbent polymer, wherein said aluminum salt further comprises a deprotonated hydroxyl mono-carboxylic acid or its salt, and wherein the aluminum salt is in the form of an aqueous solution having a pH value from about 5.5 to about 7
• wherein said aluminum salt solution comprises aluminum cations and anions of a deprotonated hydroxyl mono-carboxylic acid with a molar ratio of carboxylic anions to aluminum cations between about 0.75:1 to about 1.5:1, wherein the superabsorbent polymer composition has a degree of neutralization of from about 50 mol % to about 80 mol %;
• and the particulate superabsorbent polymer composition have a Gel Bed Permeability of from about 30 Darcy to about 100 Darcy as measured by the Free-Swell Gel Bed Permeability Test set forth herein;
• a Centrifuge Retention Capacity of from about 25 g/g to about 50 g/g as measured by the Centrifuge Retention Capacity Test set forth herein, and an absorbency under load at 0.9 psi from about 16 g/g to 24 g/g as measured by the Absorbency Under Load Test (AUL(0.9 psi)) set forth herein.

A process for the production of a particulate superabsorbent polymer composition comprising the following steps:

• a) providing a particulate superabsorbent polymer;
• b) preparing a neutralized multivalent metal salt wherein said neutralized multivalent metal salt further comprises a deprotonated organic acid or its salt, wherein the molar ratio of said organic acid to multivalent metal is between about 0.75:1 to about 1.5:1, and wherein the neutralized multivalent metal is in the form of an aqueous solution having a pH value from about 5.5 to about 7;
• c) applying the neutralized multivalent metal salt solution on the surface of the particulate superabsorbent polymer wherein
• wherein the particulate superabsorbent polymer composition has a degree of neutralization of from about 50 mol % to about 80 mol %;
• and the particulate superabsorbent polymer composition has the characteristics of a Gel Bed Permeability of from about 30 Darcy to about 100 Darcy as measured by the Free-Swell Gel Bed Permeability Test set forth herein;
• a Centrifuge Retention Capacity from about 25 g/g to about 50 g/g as measured by the Centrifuge Retention Capacity Test set forth herein, and an absorbency under load at 0.9 psi from about 16 g/g to 24 g/g as measured by the Absorbency Under Load Test (AUL(0.9 psi)) set forth herein.

A process for the production of a particulate superabsorbent polymer composition comprising the following steps:

• a) providing a particulate superabsorbent polymer;
• b) bringing the superabsorbent polymer into contact with an aqueous solution of comprising a multivalent cation and an anion of a deprotonated organic acid with a molar ratio of organic acid to multivalent cation between about 0.75:1 to about 1.5:1;
• wherein said aqueous solution has a pH value from about 5.5 to about 7;
• and said organic acid is a hydroxyl mono-carboxylic acid
• wherein the particulate superabsorbent polymer composition has a degree of neutralization of from about 50 mol % to about 80 mol %;
• and the particulate superabsorbent polymer composition has the characteristics of a Gel Bed Permeability of from about 30 Darcy to about 100 Darcy as measured by the Free-Swell Gel Bed Permeability Test set forth herein;
• a Centrifuge Retention Capacity from about 25 g/g to about 50 g/g as measured by the Centrifuge Retention Capacity Test set forth herein, and an absorbency under load at 0.9 psi from about 16 g/g to 24 g/g as measured by the Absorbency Under Load Test (AUL(0.9 psi)) set forth herein.