Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2001-07-19
2002-11-19
Acquah, Samuel A. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C528S425000, C528S503000, C522S074000, C522S100000, C522S179000
Reexamination Certificate
active
06482870
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
BACKGROUND—FIELD OF INVENTION
This invention relates generally to a method for producing a polyethylene oxide network, by using a Dialkyl Peroxide, which can swell in water to form a hydrogel and absorb large amount of water.
BACKGROUND—DESCRIPTION OF PRIOR ART
Crosslinking of PEO was first reported by researchers at Union Carbide, U.S. Pat. No. 3,264,202, in Aug. 2, 1966. Crosslinking had been brought about by gamma radiation of dilute aqueous solutions of PEO. Later, methods based on chemical crosslinking via hydroxyl end groups in PEO was suggested by Gnanou et al, Macromolecules, 17, 945 (1984). Recently, Doytcheva et al, reported crosslinking of PEO by ultraviolet irradiation, J. Appl. Polym Sci 64, 2299 (1997). Crosslinking of PEO by gamma radiation was restricted to dilute aqueous solutions, almost 0.8 to 8% PEO by weight, although higher values also are reported (U.S. Pat. No. 5,645,583). Crosslinking in bulk required more than 100 Mrad dosage, which is impractical. This way of network formation is not very attractive for large production rates for super absorbent technology like baby diapers or hygienic products.
Moreover, crosslinking by ultraviolet radiation is restricted to very thin layers, as thin as 160-250 micrometer, and that is also not applicable for high production rates or thick layers.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a process for producing a hydrogel by peroxide crosslinking of polyethylene oxide.
Another object of this invention is to provide a chemical method for crosslinking of PEO that is cheap and easy for large scale production.
A further object of the present invention is to provide a highly swollen gel which is very soft and can be used in superabsorbent technology or in biomedical applications, like wound healing after purification and sterilization.
REFERENCES:
patent: 3264202 (1966-08-01), King
patent: 4684558 (1987-08-01), Keusch et al.
patent: 5147646 (1992-09-01), Graham
patent: 5645583 (1997-07-01), Villain et al.
Emami Shahriar Hojjati
Salovey Ronald
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