Method of manufacturing water-absorbent resin, water-absorbent resin, water-absorbing agent and absorbent article

Patent metadata

Field	Value
Publication number	US-9873755-B2
Application number	US-201414787716-A
Country	US
Kind code	B2
Filing date	Nov 4, 2014
Priority date	Jul 11, 2014
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

With respect to water-absorbent resins, there are provided a method of manufacturing a water-absorbent resin having an appropriate BET specific surface and a water-absorption rate and a water-absorbing agent and an absorbent article that are formed by using the water-absorbent resin. In a first aspect of the present invention, when reverse phase suspension polymerization of two steps or more is performed on a water-soluble ethylenically unsaturated monomer in a hydrocarbon dispersion medium in the presence of at least an azo compound, a peroxide and an internal-crosslinking agent, the used amount of the internal-crosslinking agent at the time of the polymerization of a first step is adjusted to fall within a range of 0.015 to 0.150 mmol per mole of the water-soluble ethylenically unsaturated monomer used at the time of the polymerization of the first step and he polymerization is performed such that, the BET specific surface area of secondary particles formed by agglomeration of primary particles obtained is controlled.

First claim

The invention claimed is:

1. A water-absorbent resin that is obtained by polymerizing a water-soluble ethylenically unsaturated monomer in presence of an internal-crosslinking agent, wherein
a monomer of 70 to 100 mol % in the water-soluble ethylenically unsaturated monomer is acrylic acid or salt thereof,
a water-absorption rate of physiological saline in the water-absorbent resin is 40 to 80 seconds,
a mass proportion of particles from 150 to 850 μm in diameter in the entire water-absorbent resin is 85 mass % or more, and a mass proportion of particles from 300 to 400 μm in diameter is 20 mass % or more and
a BET specific surface area of particles classified into 300 to 400 μm is less than 0.03 m 2 /g.

2. The water-absorbent resin according to claim 1 , wherein a median particle diameter of the water-absorbent resin is 200 to 600 μm.

3. A water-absorbing agent that is obtained by mixing the water-absorbent resin according to claim 1 with an inorganic fine powder.

4. An absorbent article that is formed by using an absorbent material containing the water-absorbent resin according to claim 1 .

5. An absorbent article that is formed by using an absorbent material containing the water-absorbing agent according to claim 3 .

6. The water-absorbent resin according to claim 1 , wherein a water-absorption rate of physiological saline in the water-absorbent resin is 43 to 80 seconds.

7. The water-absorbent resin according to claim 1 , wherein the water-absorbent resin is obtained by polymerizing a water-soluble ethylenically unsaturated monomer in presence of an azo compound, a peroxide and an internal-crosslinking agent.

8. A method of manufacturing the water-absorbent resin of claim 7 , wherein when reverse phase suspension polymerization of two steps or more is performed on a water-soluble ethylenically unsaturated monomer in a hydrocarbon dispersion medium in presence of at least an azo compound, a peroxide and an internal-crosslinking agent,
the polymerization at each step being performed in the presence of an azo compound and a peroxide,
a used amount of the internal-cros slinking agent at the time of the polymerization of a first step for 1 mole of the water-soluble ethylenically unsaturated monomer used at the time of the polymerization of the first step is adjusted to fall within a range of 0.015 to 0.150 mmol and the polymerization is performed such that a BET specific surface area of secondary particles formed by agglomeration of primary particles obtained is controlled.

9. The method of manufacturing a water-absorbent resin according to claim 8 , wherein a used amount (mole) of the internal-crosslinking agent at the time of the polymerization of the second and later steps for 1 mole of the water-soluble ethylenically unsaturated monomer of the second and later steps, is 90% or less of a used amount (mole) of the internal-crosslinking agent used at the time of the polymerization of the first step for 1 mole of the water-soluble ethylenically unsaturated monomer used at the time of the polymerization of the first step.

10. The method of manufacturing a water-absorbent resin according to claim 8 , wherein the BET specific surface area of the secondary particles that are formed by agglomeration of the primary particles and that are classified into 300 to 400 μm is controlled to be less than 0.03 m 2 /g.

Assignees

• Sumitomo Seika Chemicals

Inventors

• Murakami Masahiro
• Hinayama Tetsuhiro
• YABUGUCHI Hiroki
• Yokoyama Hideki

Classifications

• A61F2013/530481

  having superabsorbent materials, i.e. highly absorbent polymer gel materials · CPC title

• C08F6/18

  Increasing the size of the dispersed particles · CPC title

• C08F4/04

  Azo-compounds · CPC title

• C08F2/44

  Polymerisation in the presence of compounding ingredients, e.g. plasticisers, dyestuffs, fillers · CPC title

• C08F2/20 Primary

  with the aid of macromolecular dispersing agents · CPC title