Absorbent articles comprising supercritical fluid treated HIPE, I-HIPE foams and other foams
The present invention comprises compositions and methods of making high internal phase emulsion foam (HIPE) and inverse high internal phase emulsion foam (I-HIPE) using super critical fluids. Such foams may be used in a wide variety of articles such as absorbent articles.
1. A method of making an absorbent foam comprising:
a) combining a water phase and a super critical fluid phase, said water phase comprising effective amounts of at least one superabsorbent precursor monomer; and
b) combining an oxidizing initiator in one of the super critical fluid phase and water phase, and a reducing initiator in the other of the supercritical fluid phase and water phase, whereby the super critical fluid phase and the water phase form an emulsion, such that polymerization of the at least one superabsorbent precursor monomer takes place in the water phase to form a polymerized material.
2. The method of claim 1 , wherein the super critical fluid phase contains an oxidizing initiator and the water phase contains a reducing initiator.
3. The method of claim 1 , wherein the super critical fluid phase contains a reducing initiator and the water phase contains an oxidizing initiator.
4. The method of claim 1 , further comprising a chemical crosslinker in at least one of the super critical fluid phase and water phase.
5. The method of claim 4 , wherein the polymerized material is cured so that the chemical crosslinker crosslinks the polymerized material.
6. The method of claim 4 , wherein curing the polymerized material comprises heating the polymerized material to a temperature of at least about 100° C.
7. The method of claim 4 , wherein curing the polymerized material comprises applying energy in the form of at least one of radiofrequency radiation, ultrasound, an electron beam, gamma radiation, and ultraviolet or visible light.
8. The method of claim 1 , further comprising an oil phase.
9. The method of claim 1 , further comprising providing an electrolyte in the water phase.
10. The method of claim 9 , wherein the electrolyte is selected from alkali metal salts, ammonium salts, amine salts, and salts of carboxylic acids.
11. The method of claim 1 , wherein at least a portion of the unpolymerized material comprising an unreacted portion of the super critical fluid phase is removed.
12. The method of claim 1 , wherein at least a portion of the unpolymerized material comprises an unreacted portion of the water phase is removed.
13. The method of claim 11 , wherein removing at least a portion of the unpolymerized material comprises heating the unpolymerized material.
14. The method of claim 12 , wherein removing at least a portion of the unpolymerized material comprises heating the unpolymerized material.
15. The method of claim 11 , wherein removing at least a portion of the unpolymerized material comprises non-compressive drying of the polymerized material.
16. The method of claim 1 , further comprising combining absorbent fibers with one of the water phase, the super-critical fluid phase, or the supercritical fluid-in-water emulsion.
17. The method of claim 16 , wherein the absorbent fibers comprise cellulosic fibers.
18. The method of claim 1 , further comprising combining insoluble particles with one of the water phase, the super-critical fluid phase, the water-in-super critical fluid phase or the super critical fluid-in-water emulsion.
19. The method of claim 1 , further comprising molding the polymerized material to have a non-planar, three-dimensional shape.
20. The method of claim 1 , wherein the at least one superabsorbent precursor monomer comprises a rubbery monomer.
21. The method of claim 1 , wherein the at least one superabsorbent precursor monomer comprises an organic unsaturated carboxylic acid or salt thereof.
22. The method of claim 1 , wherein the at least one superabsorbent precursor monomer comprises at least one of acrylic acid, methacrylic acid, maleic acid, itaconic acid, and salts thereof.