Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Patent
1998-06-18
2000-08-08
Cooney, John
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
521 54, 521 64, 521149, 264140, 264165, C08J 936
Patent
active
061003050
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process for producing water-absorbent resins suitable for use in various applications, for example, sanitary materials (such as paper diapers and incontinence pads), water retentive material for soil, freshness retentive materials for food, and water retentive materials for agricultural and horticultural use, by crushing a mass of crosslinked hydrogel polymer of high adhesion properties and elastic properties, without kneading it.
BACKGROUND OF THE INVENTION
It is well known that a crosslinked hydrogel polymer as a water-absorbent crosslinked polymer is obtained by aqueous solution polymerization of a water-soluble ethylenically unsaturated monomer under the presence of a small amount of crosslinking agent. The crosslinked hydrogel polymer is a highly elastic semisolid gel material, and is rarely used as it is. In many cases, in order to increase the drying efficiency, the crosslinked hydrogel polymer is once crushed (granulated), and then dried and ground. Namely, the crosslinked hydrogel polymer in the form of dried powder is used as an water-absorbent resin, i.e., water-absorber.
As a method of crushing a mass of the crosslinked hydrogel polymer in the above-mentioned process, for example, it is possible to use known methods, for example, 1 crushing the crosslinked hydrogel polymer after polymerization by a screw-type extruder such as a meat chopper, 2 crushing the crosslinked hydrogel polymer during polymerization in the kneader, 3 chopping the crosslinked hydrogel polymer after polymerization with hands using scissors, and 4 cutting the crosslinked hydrogel polymer while pressing a ring-shaped cutting edge against a counter roll.
However, when crushing the crosslinked hydrogel polymer obtained by aqueous solution polymerization using a meat chopper or kneader, the crosslinked hydrogel polymer is crushed while being compressed and kneaded. Therefore, when the above-method 1 or 2 is adopted, a very strong mechanical external force acts on the crosslinked hydrogel polymer. Consequently, there is a possibility that the crosslinked polymer chain is cut, and the water-soluble component content increases.
In resent years, in order to prevent clothes, etc. from being made dirty by body exudates such as urine and blood, particulate water-absorbent resins for absorbing and holding such body exudates are widely used as a component member of sanitary materials such as paper diapers, sanitary napkins, and incontinence pads. Moreover, there has been a recent trend toward decreasing the fiber base material such as pulp and increasing the water-absorbent resin content of the sanitary materials in order to decrease the thickness and improve the performance of the sanitary materials. Thus, there is demand for a further improvement of the absorption properties of the water-absorbent resin. Such demand can be satisfied by improving the absorption properties, more particularly water absorbing capacity and absorption rate. For example, according to a known method for improving the absorption properties, the surface area of the water-absorbent resin is increased. However, if the surface area is increased by simply decreasing the particle diameter of the particulate water-absorbent resin, the liquid permeability in the water-absorbent resin is worsened.
As a method for increasing the surface area without decreasing the particle diameter, for example, Japanese publication of unexamined patent application (Tokukaihei) Nos. 5-237378 and 7-185331, and publication of international application No. WO95/02002 proposed a method for producing a water-absorbent resin in the form of porous particles by causing the particles of the water-absorbent resins to contain cells therein using a blowing agent during polymerization or crosslinking.
Thus, in a suitable method for improving the absorption properties of a water-absorbent resin, a crosslinked hydrogel polymer is formed by aqueous solution polymerization of, for example, a water-soluble ethylenically unsaturated monomer under the
REFERENCES:
patent: 3720534 (1973-03-01), Macaulay et al.
patent: 4690788 (1987-09-01), Yada et al.
patent: 5118719 (1992-06-01), Lind
patent: 5314420 (1994-05-01), Smith et al.
patent: 5328935 (1994-07-01), Van Phan et al.
patent: 5338766 (1994-08-01), Phan et al.
patent: 5451613 (1995-09-01), Smith et al.
patent: 5712316 (1998-01-01), Dahmen et al.
patent: 5859077 (1999-01-01), Reichman et al.
Harada Nobuyuki
Kanto Teruyuki
Miyake Koji
Motono Yoshihiro
Sakamoto Shigeru
Cooney John
Nippon Shokubai Co. , Ltd.
LandOfFree
Method of production of water-absorbing resin does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of production of water-absorbing resin, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of production of water-absorbing resin will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1150675