Crosslinker for superabsorbent polymers

A technology of cross-linking agent and compound, which is applied in the direction of absorbent pads, medical science, bandages, etc., can solve the problems of increasing uncross-linked polymers, no superabsorbent polymers, and undesirable degree of polymer decomposition, and achieve easy processing Effect

Inactive Publication Date: 2007-12-26
EVONIK DEGUSSA GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Unfortunately, for commercially useful crosslinkers, heating the polymer sufficiently to achieve this within an acceptable time would result in an undesired degree of polymer decomposition
Another potential route to achieve low crosslink density is to simply use low levels of crosslinker; however, this leads to gels that are difficult to process in the reactor and an undesired increase in uncrosslinked polymer
[0005] WO 02 / 04548 A1 discloses the use of specific heat-labile crosslinkers in the production of solid polymer coatings, but does not refer to the application of said substances in the manufacture of superabsorbent polymers

Method used

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  • Crosslinker for superabsorbent polymers
  • Crosslinker for superabsorbent polymers
  • Crosslinker for superabsorbent polymers

Examples

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preparation example Construction

[0030] In the preparation of the crosslinking agent, an inert polar or nonpolar solvent is suitably used. Examples of suitable solvents include toluene, dichloromethane, chloroform and tetrahydrofuran. Combinations of solvents can be used. The amount of solvent used is not critical as long as it is sufficient to dissolve the reagents. The concentration of reagents in the reaction mixture is preferably from about 0.01 molar to about 10 molar, more preferably from about 0.2 molar to about 4 molar.

[0031] Acryloyl chloride or methacryloyl chloride and reagent (I + ), (II + ) or (III + ) is an exothermic reaction. Therefore, the reaction temperature is preferably controlled so that the temperature does not reach the point where thermal polymerization occurs. The reaction temperature is not critical as long as the reaction can proceed. Preferably, the temperature of the reaction mixture is from about 15°C to about 55°C.

[0032] Any reaction time can be used; however, gen...

Embodiment 1

[0085] A 1 L jacketed, bottom venting reactor was equipped with nitrogen inlet, heat trap, inclined paddle turbine type stirrer and addition funnel. The apparatus was purged with nitrogen overnight before use. The reactor was charged with 200 ml of toluene and 28.3 g (0.27 mol) of 3-methyl-1,3-butanediol. With stirring, 84.3 g (0.83 mol) of triethylamine were added, forming a clear, colorless solution without increasing the temperature. The solution was heated to 35°C. A solution of 109.4 g (1.21 mol) of 96% acryloyl chloride dissolved in 100 ml of toluene was added dropwise. A precipitate formed immediately and the reaction temperature increased. The reaction temperature was maintained between 45°C and 50°C by jacket cooling. When the addition was complete, the mixture was heated at 48°C for 3 hours.

[0086] The mixture was cooled to 35°C and 500 ml of deionized water was added. In order to dissolve the precipitate, the mixture was stirred at 35°C for 45 minutes. The ...

Embodiment 2

[0088] A 500ml 3 neck round bottom flask was equipped with nitrogen inlet, magnetic stir bar, addition funnel, temperature probe and stopper. 150 ml of toluene and 28.3 ml (0.30 mol) of 97% acryloyl chloride were added to the flask. Via syringe, 10.6 ml (0.10 mol) of 3-methyl-1,3-butanediol were added. The resulting solution was heated to 40°C. A solution of 30.6 ml (0.22 mol) of triethylamine in 100 ml of toluene was added at a slow drop rate with vigorous stirring. The reaction was exothermic, with the temperature rising to 50°C. The reaction temperature was maintained at about 50°C by cooling in a water bath. During the addition, a flocculent precipitate formed. When the addition was complete, the slurry was maintained at about 50°C for 2 hours by means of a water bath. After cooling to room temperature, the precipitate was removed by filtration. Volatiles were removed from the filtrate under vacuum to leave a pale yellow, slightly cloudy liquid. The product was diss...

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Abstract

The crosslinker of the invention is an asymmetrical polyvinyl crosslinker that disassociates at elevated temperature, and is especially useful in the preparation of superabsorbent polymers.

Description

technical field [0001] The present invention relates to compounds useful as crosslinking agents in the manufacture of water-swellable, water-insoluble polymers. Background technique [0002] Superabsorbent polymers are well known materials commonly used in, for example, cable covers, produce, packaging and personal care products such as diapers. These polymers are believed to absorb many times their weight in body fluids such as water, saline solution, urine, blood and serous body fluids. [0003] During the manufacture of such polymers, it is desirable to produce hydrogels with high crosslink density in the polymerization reactor, as this provides easily processable hydrogels. It is known that absorbency is inversely proportional to crosslink density, ie a hydrogel with a desirably high crosslink density will have a low absorbency. Manufacturers of absorbent articles and devices, however, prefer final polymer products with high absorbent capacity (ie low crosslink density...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): A61L15/00C08K5/103
CPCC08K5/103
Inventor T·H·纽曼
Owner EVONIK DEGUSSA GMBH
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