Superabsorbent polymer and method of producing the same
A superabsorbent polymers and a method of forming the same are provided. The method is processed by adding calcined shell powders to a free radical polymerization. The superabsorbent polymers with more micropores can be obtained. Therefore, absorptivity and permeability for the liquid of the superabsorbent polymers are increased, and diffusibility and liquid conductivity of the superabsorbent polymers are also improved.
1. A method of producing superabsorbent polymer, comprising:
performing a free radical polymerization reaction to a superabsorbent polymer composition and calcined shell powders to obtain a colloid gel, wherein the superabsorbent polymer composition includes an unsaturated monomer aqueous solution, a polymerization initiator, and a free radical polymerization crosslinking agent, the calcined shell powders comprise calcium carbonate, the calcined shell powders have a core-shell structure, the calcined shell powders have a particle size of 100 μm to 1 mm, and based on an amount of the unsaturated monomer aqueous solution as 100 wt %, the amount of the calcined shell powders is 0.005 wt % to 10 wt %;
smashing and screening the colloid gel to obtain a plurality of superabsorbent polymer particles; and
performing a surface crosslinking reaction to the superabsorbent polymer particles to obtain the superabsorbent polymer.
2. The method of claim 1 , wherein a core of the core-shell structure is a micron particle of calcium carbonate, a shell layer of the core-shell structure is nanometer to sub-micron particles of calcium carbonate, an average particle size of the core is 7 μm to 500 μm, and an average particles size of the shell layer is not greater than 200 nm.
3. The method of claim 1 , wherein whiteness of the calcined shell powders is at least 60.
4. The method of claim 1 , wherein the specific surface area of the calcined shell powders is at least 8000 cm 2 /g.
5. The method of claim 1 , wherein the calcined shell powders are added before, during or after the free radical polymerization reaction is performed.
6. The method of claim 1 , wherein pH value of the unsaturated monomer aqueous solution is 5.5 to 7.0.
7. The method of claim 1 , wherein the polymerization initiator comprises a thermal decomposition initiator, a redox initiator or a combination thereof.
8. The method of claim 1 , wherein based on the amount of the unsaturated monomer aqueous solution as 100 wt %, the amount of the polymerization initiator is 0.001 wt % to 10 wt %.
9. The method of claim 1 , wherein based on the amount of the unsaturated monomer aqueous solution as 100 wt %, the amount of the free radical polymerization crosslinking agent is 0.001 wt % to 5 wt %.
10. The method of claim 1 , further comprising:
drying the colloid gel at a temperature of 100° C. to 250° C. before smashing and screening the colloid gel.
11. The method of claim 1 , wherein the average particle size of the superabsorbent polymer particles is 0.06 mm to 1.00 mm.
12. The method of claim 1 , wherein based on the amount of the superabsorbent polymer particles as 100 wt %, the amount of the surface crosslinking agent is 0.001 wt % to 10 wt %.