POLYACRYLIC ACID (SALT) -BASED WATER-ABSORBENT RESIN AND A METHOD FOR PRODUCING IT
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Abstract
The purpose of the present invention is to improve the water absorption of a water-absorbent resin without sacrificing the productivity, production cost, safety, and so on. Provided is a sustainable and renewable water-absorbent resin with excellent whiteness, which is suitable for mass consumption as disposal diapers or the like, and which can dispense with excessive purification of raw material acrylic acid. Also provided is a process for the production of a water-absorbent resin, which comprises: a step of preparing acrylic monomers; a step of polymerizing the monomers; and a step of drying the obtained aqueous gel, wherein the monomers at the time of polymerization contain at least 400 ppm of propionic acid.
15 Citations
50 Claims
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1-30. -30. (canceled)
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31. A method for producing a polyacrylic acid (salt)-based water-absorbent resin, the method comprising:
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a preparation step in which a monomer is prepared from acrylic acid containing propionic acid; a polymerization step in which the monomer is polymerized; and a drying step in which an obtained hydrogel is dried, wherein Fe (on the basis of Fe2O3) in the monomer is 0.002 to 2 ppm by mass; a plurality of acrylic acids having different propionic acid amounts of 1.1 to 50 times by mass are mixed to prepare the monomer; a plurality of acrylic acids obtained by different production processes of at least one selected from plant, installation site, raw material, oxide type, and refining type are mixed to prepare the monomer; and propionic acid is removed from polyacrylic acid (salt) during polymerization or after polymerization. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44)
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45. A method for producing a polyacrylic acid (salt)-based water-absorbent resin, the method comprising:
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a preparation step in which a monomer is prepared from acrylic acid; a polymerization step in which the monomer is polymerized; and a drying step in which an obtained hydrogel is dried, wherein Fe (on the basis of Fe2O3) in the monomer is 0.002 to 2 ppm by mass; the monomer at the time of polymerization contains 500 ppm to 1 mass % of propionic acid (C2H5COOH); and the propionic acid is removed from the polyacrylic acid (salt) during polymerization or after polymerization.
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- 46. A polyacrylic acid (salt)-based water-absorbent resin using acrylic acid derived from a non-fossil raw material and acrylic acid derived from a fossil raw material at 1/99 to 99/1 (mass ratio) in combination.
Specification