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US 2026/0208158 A1Published application
Process for the production of superabsorbents
AssigneeBASF SE
InventorsDieter SCHILLER, Ivanilton Dos Reis SOUZA, Helvio VIEIRA AMORIM, Francisco Assis DA SILVA JUNIOR
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Abstract
The present invention relates to a process for producing superabsorbents, wherein a monomer solution M is cooled by a heat exchanger W, the neutralization is interrupted to clean the heat exchanger W, and the heat exchanger W is emptied, filled with water or an aqueous solution and blow-dried.
Claims15
1:
- A process for producing superabsorbents by, comprising:
- at least partly neutralizing at least one ethylenically unsaturated monomer bearing acid groups with an aqueous base;
- cooling a resultant aqueous monomer solution M with a heat exchanger W;
- adding at least one crosslinker and at least one initiator to the aqueous monomer solution M;
- then polymerizing the aqueous monomer solution M to a polymer gel;
- optionally extruding the polymer gel;
- drying the polymer gel;
- and
- comminuting, classifying and optionally thermally surface postcrosslinking the dried polymer gel;
- wherein:
- the neutralization is stopped for cleaning of the heat exchanger W;
- and
- the heat exchanger W is emptied, filled with water or an aqueous solution and cleared by blowing.
10 more elements
2:
- The process according to claim 1, wherein the heat exchanger W is at least twice filled with water or an aqueous solution and cleared by blowing.
3:
- The process according to claim 1, wherein the heat exchanger W is additionally filled with an alkaline solution, heated, and emptied.
4:
- The process according to claim 3, wherein the heat exchanger W is at least twice filled with an alkaline solution, heated, and emptied.
5:
- The process according to claim 3, wherein the alkaline solution a sodium hydroxide solution.
6:
- The process according to claim 5, wherein the sodium hydroxide solution has a sodium hydroxide content of at least 40% by weight.
7:
- The process according to claim 3, wherein the alkaline solution is heated to at least 60° C. in the heat exchanger W.
8:
- The process according to claim 3, wherein the alkaline solution is heated for at least 25 minutes in the heat exchanger W.
9:
- The process according to claim 1, wherein a plate heat exchanger is used as heat exchanger W.
10:
- The process according to claim 1, wherein the ethylenically unsaturated monomer bearing acid groups used is an ethylenically unsaturated carboxylic acid.
11:
- The process according to claim 1, wherein the ethylenically unsaturated monomer bearing acid groups used is acrylic acid.
12:
- The process according to claim 1, wherein the base comprises at least one selected from the group consisting of an alkali metal hydroxide, an alkali metal oxide, an alkali metal hydrogencarbonate, and an alkali metal carbonate.
13:
- The process according to claim 1, wherein the base is sodium hydroxide.
14:
- The process according to claim 1, wherein the ethylenically unsaturated monomer bearing acid groups is neutralized to an extent of 60 to 75 mol %.
15:
- The process according to claim 1, wherein a water content of the monomer solution M is 50% to 65% by weight.