A continuous process for the production of a superabsorbent polymer

A polymer, mixture technology, used in absorbent pads, medical science, bandages, etc., can solve problems such as inertization of monomer mixtures

Active Publication Date: 2011-09-07
EVONIK SUPERABSORBER GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In WO-A-2007 / 028748 this problem is solved by adding polymerization inhibitors and by incompletely inerting the monomer mixture, but the disadvantage of this technique is that there is then considerable Large amounts of oxygen and polymerization inhibitors

Method used

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  • A continuous process for the production of a superabsorbent polymer
  • A continuous process for the production of a superabsorbent polymer

Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0068] It is preferred for smooth production conditions to have a buffer vessel of polymer gel downstream in the process between the reactor and the next unit. In addition to holding the desired amount of buffer material, the container also acts as a storage tank to further allow for a conversion of the polymer gel of greater than 99%, more preferably greater than 99.5%. Furthermore, additional locations are provided where additives can be introduced into the polymer and mixed in. The design of the vessel is not critical as long as means are provided for adequate agitation and maintaining the desired gel temperature. The vessel is preferably insulated to maintain the gel at the desired temperature, permits substantial plug flow, and is designed so that the polymer gel can be continuously and reliably charged and discharged. The containers may be horizontally or vertically arranged containers, single or multi-screw conveyors or moving belts. The container can supply multiple ...

Embodiment 1

[0160]Example 1 (deoxygenation in 250 ml glass reactor; reference example)

[0161] By mixing 86.67 grams of 99.8% active ingredient acrylic acid, 60.55 grams of 50% active ingredient NaOH, 77.7 grams of water, 0.23 grams of highly ethoxylated trimethylolpropane triacrylate having an average of 15 EO units in the molecule (HE-TMPTA) and 0.87 grams of PEG 600 to prepare a monomer solution. Particles are not dispersed therein. The monomer solution was charged to a 250 ml glass reactor equipped with a magnetic stir bar and a lid with 3 openings. One opening bears a membrane-covered electrochemical sensor inserted into the monomer solution for oxygen measurement. One opening is equipped with a gas check valve and is used to vent gas. The final degree of neutralization was brought to a level of 70% by adding 22.9 grams of 20% aqueous sodium carbonate solution through a third valve with gentle stirring of the monomer solution. After adding carbonate solution (Na 2 CO 3 ) begin...

Embodiment 2

[0164] Embodiment 2 (reference embodiment)

[0165] Example 1 was repeated except that 86.67 grams of 99.8% active acrylic acid and 68.79 grams of 49% active NaOH were used, and 34.67 grams of scrubbing water were added instead of the carbonate solution. Due to the presence of carbonates in the scrubbing water, its contact with the prepared monomer solution showed the same release of CO as in the previous examples. 2 Reaction. The oxygen concentration in the mixture drops, as shown in Table 2. As in Example 1, add 0.05 g of 35% active ingredient H 2 o 2 solution, 1.3 g of 10% active ingredient Na 2 S 2 o 8 and 0.34 g of a 1% active ingredient in ascorbic acid solution immediately initiated the polymerization process and heated the reaction mass to a peak temperature of 115° C. within 3 minutes.

[0166] Table 2

[0167] Time after adding scrubbing water (min)

[0168] Reference Examples 1 and 2 relate to a batch process and are therefore not examples accordin...

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Abstract

The present invention relates to a continuous process for the production of a superabsorbent polymer comprising: (a) providing an acidic liquid aqueous monomer mixture containing dissolved oxygen, whereby the monomers are selected to provide after polymerization a superabsorbent polymer, (b) continuously feeding said aqueous monomer mixture to a reactor, (c) introducing a source of carbonate or hydrogen carbonate into said aqueous monomer mixture prior to entry into the reactor thereby forming a gas phase comprising carbon dioxide and at least a part of said dissolved oxygen, said gas phase being dispersed in the liquid phase, (d) subjecting the gas/liquid mixture to at least partial phase separation immediately prior to or after entry into the reactor and at least partially removing the separated gaseous phase, (e); subjecting the liquid phase in the reactor to free-radical polymerization to obtain the superabsorbent polymer, and (f) continuously removing the superabsorbent polymer from the reactor.

Description

technical field [0001] The present invention relates to a continuous process for the preparation of superabsorbent polymers. Background technique [0002] The preparation of water-absorbing polymers is summarized, for example, in "Modern Superabsorbent Polymer Technology" by F.L. Buchholz and A.T. Graham, Wiley-VCH, 1998 or Ullmann's Encyclopedia Industrial Chemistry, 6th Edition, Vol. 35, pp. 73-103. The preferred method of preparation is solution or gel polymerization. If this technique is used, the resulting monomer mixture is usually neutralized in batches, then transferred to a polymerization reactor, and then polymerized batchwise or continuously to a polymer gel, which is comminuted under stirring polymerization . The polymer gel is then dried, ground and screened, and optionally surface treated. [0003] Processes for continuous polymerization are described, for example, in WO-A-01 / 38402, WO-A-03 / 004237, WO-A-03 / 022896 and WO-A-01 / 16197. [0004] Because solution...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): A61L15/60C08F2/10C08F20/06C08J11/00
CPCC08F220/06C08F2/10C08L101/14C08F222/1006C08F4/40C08F222/103
Inventor D·弗里克H·A·加特纳M·阿热J·哈伦H-P·科勒H·普洛钦格
Owner EVONIK SUPERABSORBER GMBH
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