Superabsorbent polymer with high permeability

The superabsorbent polymer composition comprising a superabsorbent polymer consisting essentially of:

• a) from about 55 to about 99.9 wt. % of polymerizable unsaturated acid group containing monomers;
• b) from about 0.001 to about 5.0 wt. % based on the weight of a) of internal crosslinking agent;
• wherein elements a) and b) are polymerized and prepared into superabsorbent polymer particles;
• wherein the superabsorbent polymer particles further comprise the following surface additives
• c) from about 0.001 to about 5.0% by weight of surface crosslinking agent applied to the particle surface based on dry polymer powder weight;
• d) from about 0.01% to about 5% by weight of a penetration modifier immediately before, during or immediately after the surface crosslinking step based on dry polymer powder weight;
• e) from 0 to about 5% by weight of a multivalent metal salt on the particle surface based on dry polymer powder weight;
• f) from 0 to 2% by weight of a surfactant on the particle surface based on dry polymer powder weight;
• g) from about 0.01 to about 5% by weight of an insoluble, inorganic powder based on dry polymer powder weight;
• and
• h) from about 0.01 to 0.5% by weight of a thermoplastic polymer based on dry polymer powder weight, the thermoplastic polymer having a thermoplastic melt temperature wherein the thermoplastic polymer is applied on and fully encapsulates the particle surface coincident with or followed by a temperature at least about the thermoplastic melt temperature or greater,
• wherein the composition has a degree of neutralization of more than about 25%;
• having the characteristics of centrifuge retention capacity of about 25 g/g or more;
• a gel bed permeability I of about 200×10−9 cm2 or more;
• or a gel bed permeability II of about 150×10−9 cm2 or more.

A method to make a superabsorbent polymer composition comprising the steps of:

• a) preparing a superabsorbent polymer by the process of polymerizing from about 55 to about 99.9% weight of polymerizable unsaturated acid group containing monomers, and from about 0.001 to about 5% weight of internal crosslinking agent based on the polymerizable unsaturated acid group containing monomers, and a neutralization such that the superabsorbent polymer has a degree of neutralization of more than about 25%;
• b) preparing superabsorbent polymer particles from the superabsorbent polymer;
• c) treating the superabsorbent polymer particles with surface additives including
• i) from about 0.001 to about 5.0% weight of a surface crosslinking agent based on dry polymer powder weight;
• ii) from about 0.01 to about 10% weight of a penetration modifier based on dry polymer powder weight;
• iii) from about 0.01 to about 5% weight of a multivalent metal salt based on dry polymer powder weight;
• iv) from 0 to 2% weight of a surfactant based on dry polymer powder weight;
• v) from about 0.01 to about 5% weight of an insoluble, inorganic powder based on dry polymer powder weight;
• and
• vi) from about 0.01 to 0.5% weight of a thermoplastic polymer based on dry polymer powder weight is applied on and fully encapsulates the particle surface, heat treating the coated superabsorbent polymer particle;
• wherein the superabsorbent polymer composition has the characteristics of centrifuge retention capacity of about 25 g/g or more;
• a gel bed permeability I of about 500×10−9 cm2 or more;
• or a gel bed permeability II of about 300×10−9 cm2 or more.