Water-absorbent agent and method for manufacturing the same
US6187872A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 6, 1998 |
| Grant date | Feb 13, 2001 |
| Priority date | — |
| Expiry date | Apr 6, 2018 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08F2810/20
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
A hydrogel polymer obtained by polymerizing a monomer component including acrylic acid (salt) is post-neutralized so that each of polymer particles derived from a polymer produced by neutralizing the hydrogel polymer has an allowable neutralization ratio. The polymer as obtained by neutralizing the hydrogel polymer is reacted with a crosslinking agent reactive to a functional group of the polymer. The allowable neutralization ratio, for example, is a neutralization ratio which is not lower, by not less than 20 mole percent, or more than, at least 55 mole percent, than an average neutralization ratio of a mass of the polymer particles, and the post-neutralization is carried out so that a number of polymer particles having a non-allowable neutralization ratio outside the allowable neutralization range is not more than 10 in 200 polymer particles, thus obtaining a water-absorbent agent having high absorbency under no applied pressure and high pressure wherein the amount of water soluble component is lower compared with the conventional water-absorbent agent and a change in pH of a swollen gel is small.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.