Water-absorbent resin powder and its production process and uses
First Claim
1. A production process for a water-absorbent resin powder, which comprises the steps of:
- polymerizing an unsaturated monomer; and
drying the resultant crosslinked hydrogel polymer, wherein the water-absorbent resin powder has a crosslinked structure and a mass-average particle diameter of 300 to 600 μ
m wherein the ratio of fine particles having particle diameters of not larger than 150 μ
m is less than 10 mass % of the water-absorbent resin powder,with the production process being characterized by further comprising a magnetic-flux irradiation step of passing a magnetic field having a magnetic flux density of not less than 0.05 Wb/m2 through the water-absorbent resin powder after the drying step in the production process.
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Abstract
The present invention provides: a water-absorbent resin powder, which includes no fine metallic foreign substance, and in which the deterioration is suppressed; its production process; and uses. The present invention production process for a water-absorbent resin powder comprises the steps of: polymerizing an unsaturated monomer; and drying the resultant crosslinked hydrogel polymer, wherein the water-absorbent resin powder has a crosslinked structure and a mass-average particle diameter of 300 to 600 μm wherein the ratio of fine particles having particle diameters of not larger than 150 μm is less than 10 mass % of the water-absorbent resin powder, with the production process being characterized by further comprising a magnetic-flux irradiation step of passing a magnetic field having a magnetic flux density of not less than 0.05 Wb/m2 through the water-absorbent resin powder after the drying step in the production process.
85 Citations
16 Claims
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1. A production process for a water-absorbent resin powder, which comprises the steps of:
- polymerizing an unsaturated monomer; and
drying the resultant crosslinked hydrogel polymer, wherein the water-absorbent resin powder has a crosslinked structure and a mass-average particle diameter of 300 to 600 μ
m wherein the ratio of fine particles having particle diameters of not larger than 150 μ
m is less than 10 mass % of the water-absorbent resin powder,with the production process being characterized by further comprising a magnetic-flux irradiation step of passing a magnetic field having a magnetic flux density of not less than 0.05 Wb/m2 through the water-absorbent resin powder after the drying step in the production process. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
- polymerizing an unsaturated monomer; and
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15. A water-absorbent resin powder, of which the major proportion is comprised of a polymer that is obtained by a process including the step of polymerizing a monomer including acrylic acid and/or its salt in a major proportion, and which has a mass-average particle diameter of 300 to 600 μ
- m wherein the ratio of fine particles having particle diameters of not larger than 150 μ
m is less than 10 mass % of the water-absorbent resin powder, and which has a crosslinked structure and is irradiated with a magnetic flux.
- m wherein the ratio of fine particles having particle diameters of not larger than 150 μ
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16. A sanitary material, comprising a water-absorbent resin powder of which the major proportion is comprised of a polymer that is obtained by a process including the step of polymerizing a monomer including acrylic acid and/or its salt in a major proportion, and which has a mass-average particle diameter of 300 to 600 μ
- m wherein the ratio of fine particles having particle diameters of not larger than 150 μ
m is less than 10 mass % of the water-absorbent resin powder, and which has a crosslinked structure and is irradiated with a magnetic flux.
- m wherein the ratio of fine particles having particle diameters of not larger than 150 μ
Specification