| abstract |
The present invention relates to a hydrogel forming polymer composition, substantially insoluble in water, slightly entangled and partially neutralized, characterized in that it consists essentially of: a) from 50 to 99,999 mole percent polymerized, unsaturated polymerizable monomers containing acidic groups and b) 0.001 to 5 molar percent of an interlock agent; said composition has a minimum degree of neutralization of at least 25 percent and is substantially free of graft-polymerizable polymeric portions; furthermore said polymer composition, after neutralization to a minimum degree of neutralization of at least 50 percent, has or may have, a gel volume of at least 20 grams, of a synthetic urine per gram of the hydrogel-forming polymer, a gel strength of such magnitude that the hydrogel, which is formed from said polymer, shows a minimum modulus of shear stress of at least 4000 drines / square cm, an initial content of extractable polymers, after one hour of being in synthetic urine , not more than about 7.5 percent by weight of the hydrogel-forming polymer and a balanced content of extractable polymers, under equilibrium conditions in synthetic urine, not more than about 17 percent by weight of the hydrogel-forming polymer. |