Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1998-04-23
2000-05-09
Niland, Patrick
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
174118, 174110V, 385115, 525119, 5253263, 5253297, 5253302, 604358, 604372, C08J 300, C08K 320, C08L 3100, C08L 3300, C08L 6300
Patent
active
06060557&
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to water-insoluble, water-swellable polymers having a high absorption capacity for water and aqueous liquids, which are based on cross-linked, hydrophilic homopolymers and copolymers, as well as on graft polymers of ethylenically unsaturated, acid groups-containing, polymerizable monomers. The present invention further relates to the production method and the use of these polymers.
Polymers absorbing large amounts of aqueous liquids, in particular body fluids such as urine, are known as superabsorbent polymers.
The absorbents are produced by radical polymerization under preferred use of monoethylenically unsaturated carboxylic acids, such as acrylic acid and its alkali salts, in aqueous solution, or according to the methods of inverse suspension or emulsion polymerization which are described in U.S. Pat. No. 4,286,082, DE 27 06 135, U.S. Pat. No. 4,340,706, DE 37 13 601, and DE 28 40 010.
Polymers having different absorption properties can produced by selection of the monomer composition, cross-linkers, and polymerization conditions and processing conditions for the polymer gel. Additional possibilities are offered by the production of graft polymers, for example, by using chemically modified starch, cellulose, and polyvinyl alcohol according to DE 26 12 846, and by aftertreating the polymer gels or powdery resins by secondary surface cross-linkage of the polymer particles, for example, according to DE 40 20 780 C1.
For application of the polymers in hygienics and the sanitary field, polymers are produced whose neutralization degree ranges between 50 and 80 mol-%, relative to the polymerized, acid groups-containing monomer units, so that hydrogels are formed which have a skin neutral effect when used.
The degree of neutralization may be adjusted in different manners, neutralization or partial neutralization of the acidic monomers frequently being carried out prior to polymerization. However, neutralization or partial neutralization of a hydrogel comprising acidic, polymerized monomer units is also known.
According to EP 205 674 A1 advantageously fully acidic polymers are produced at temperatures ranging from 0 to 100.degree. C., preferably 5 to 40.degree. C., which are adjusted by subsequent partial neutralization of the hydrogel. The polymers stand out for an improved gel strength and absorption capacity, as well as for a small portion of water-soluble polymers.
According to U.S. Pat. No. 5,145,906 and EP 530 438 B1 polymer gels of acrylic acid together with water-soluble, hydroxyl groups-containing polymers are produced at temperatures ranging from 5 to 20.degree. C. under adiabatic conditions without neutralization of the monomers; subsequently the polymer gels are reduced in size and partially or completely neutralized by aqueous bases, comminuted again in the presence of a secondary cross-linking agent, and subjected to a heat treatment.
The mentioned methods are disadvantageous;, because polymerization of the monomer solution, as is demonstrated in EP 467 073 A1, takes place very slowly so that it can only be carried out discontinuously in a batch method. Increasing the amount of initiator or elevating the reaction temperature affects the desired polymer properties. Furthermore, it is difficult to comminute the entirely acidic polymer gel, and neutralization takes place slowly because of the procedure which is governed by diffusion. In this connection, excess base remains in the surface region of the polymer particles, while still reactive, polymerized, acid groups-containing monomer units are present in the gel interior where they are not available for subsequent cross-linkage in the surface region.
EP 467 073 A1 describes polymers which are obtained at a controlled polymerization temperature in the range of 20 to 70.degree. C., in particular at 55 to 60.degree. C., within 5 hours. According to the described method the polyacrylic acid is then neutralized to a degree of 72%. The dry and ground polymer is then subjected to the subsequent cross-linking process. However, i
REFERENCES:
patent: 5145906 (1992-09-01), Chambers et al.
patent: 5610220 (1997-03-01), Klimmek et al.
patent: 5672633 (1997-09-01), Brehm et al.
patent: 5712316 (1998-01-01), Dahmen et al.
Derwent Abstracts, AN 93-252771, JP 5-170835, Nov. 22, 1993.
Patent Abstracts of Japan, vol. 14, No. 505, Nov. 5, 1990, JP 2-209906, Aug. 21, 1990.
Patent Abstracts of Japan, vol. 13, No. 515, Nov. 17, 1989, JP 1-207133, Aug. 21, 1989.
Winfried Krug, Energie- und Nachrichtenkabel langswasserdicht isolieren, pp. 34-36, Ganz Dicht?, Drahtwelt 5, 1992.
W. Schafer, et al., Werkstoffe, pp. 12-21, "Quellvliesstoffe fur langs-wasserdichte Kabelkonstruktionen", Drahtwelt 2, 1989.
Dahmen Kurt
Peppmoller Reinmar
Niland Patrick
Stockhausen GmbH & Co. KG
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