Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Patent
1998-05-04
2000-10-24
Foelak, Morton
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
521 61, 521 63, 521 64, C08J 928
Patent
active
061368733
DESCRIPTION:
BRIEF SUMMARY
The invention relates to water-absorbing, expanded, crosslinked polymers, to a process for the production thereof and to the use thereof in hygiene articles employed to absorb body fluids and in dressing material for covering wounds.
Water-absorbing, crosslinked polymers are referred to as superabsorbents or superabsorbing polymers because they are able to absorb a multiple of their own weight of aqueous liquids to form hydrogels. Superabsorbents are used in practice, for example, in diapers for absorbing urine. The superabsorbents have the property of retaining the absorbed liquid even under mechanical stress.
In order to alter the use properties of superabsorbents, two different types of foams are known: (1) mixtures which contain superabsorbents in a foamed matrix, and (2) foams which consist of a superabsorbing material.
A foam belonging to category (1) is produced, for example, from a mixture which comprises, on the one hand, components for forming a polyurethane foam and, on the other hand, polymerizable monomers, a crosslinker and a polymerization initiator to produce a superabsorbent. The foam is formed from the polyurethane components in a mixture of this type in a polycondensation reaction and contains the superabsorbent which has been produced by polymerization of the monomers in the form of an interpenetrating network, cf. U.S. Pat. No. 4,725,628, U.S. Pat. No. 4,725,629 and U.S. Pat. No. 4,731,391.
U.S. Pat. No. 4,985,467 discloses a polyurethane foam which contains a chemically bonded superabsorbent. Also known are combinations of latex foams into which superabsorbing, fine-particle materials are incorporated after the foaming process, cf. EP-A-427 219 and U.S. Pat. No. 4,990,541.
Products belonging to category (2) of foams are those, for example, which are obtained by mixing a prefabricated superabsorbent in an extruder with a polyhydroxy compound and a blowing agent at elevated temperature. The foam is formed when the mixture is expelled from the extruder. Processes of this type are described, for example, in U.S. Pat. No. 4,394,930, U.S. Pat. No. 4,415,388 and GB-A-2 136 813.
U.S. Pat. No. 4,529,739 and U.S. Pat. No. 4,649,154 disclose processes for producing foams in which a water-swellable material having COOH groups is foamed with a blowing agent which liberates the blowing gas in a neutralization reaction with the COOH groups of the polymer.
According to the statements in WO-A 94/22502, superabsorbing foams based on crosslinked, partially neutralized polycarboxylates are produced by foaming a monomer mixture with a blowing agent which is insoluble in water and has a boiling point below 50.degree. C., and completing polymerization of the foam at virtually the same time as the foaming.
EP-A-04 21 264 discloses the production of foam-like superabsorbents by polymerizing an aqueous monomer mixture which contains an emulsified oil phase. The action of the oil in this case is to occupy the space for the later pores in the foam and it is removed by evaporation, after the polymerization is complete, on drying the expanded material.
WO-A 88/09801 discloses that it is possible to process hydrophilic polymers, eg. sodium polyacrylate, in the presence of crosslinkers such as polyepoxides and blowing agents, by heating, to an expanded superabsorbent.
Another procedure known for producing expanded superabsorbents is to add carbonates, bicarbonates or carbon dioxide as blowing agents to a mixture of monomers which contain carboxyl groups, crosslinker and polymerization initiator, with the polymerization of the monomers being started at the same time as the addition of the blowing agent or shortly thereafter. The superabsorbent acquires a foam structure due to the carbon dioxide formed in the neutralization reaction, cf. U.S. Pat. No. 4,808,637. In the process disclosed in WO-A 95/02002, an expanded superabsorbent is mixed after production with one or more reactive compounds for subsequent surface crosslinking, and is heated to from 100 to 300.degree. C.
In the processes described above for producing
REFERENCES:
patent: 4394930 (1983-07-01), Korpman
patent: 4415388 (1983-11-01), Korpman
patent: 4529739 (1985-07-01), Scott et al.
patent: 4649154 (1987-03-01), Dolman et al.
patent: 4725628 (1988-02-01), Garvey et al.
patent: 4725629 (1988-02-01), Garvey et al.
patent: 4731391 (1988-03-01), Garvey et al.
patent: 4808637 (1989-02-01), Boardman et al.
patent: 4985467 (1991-01-01), Kelly et al.
patent: 4990541 (1991-02-01), Nielsen et al.
patent: 5328935 (1994-07-01), Van Phan et al.
patent: 5338766 (1994-08-01), Van Phan et al.
Anstock Thomas
Hahnle Hans-Joachim
Schornick Gunnar
Tropsch Jurgen
Walter Manfred
BASF - Aktiengesellschaft
Foelak Morton
LandOfFree
Water-absorbing, expanded, crosslinked polymers, the production does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Water-absorbing, expanded, crosslinked polymers, the production , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Water-absorbing, expanded, crosslinked polymers, the production will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1964739