Method of producing a modified smectite or smectite-containing substance capable of taking up and releasing water in a reversible manner

摘要

A method for producing a modified smectite or smectite-containing substance including treating a non-activated smectite or substance with a water soluble activating agent and polymer in a two stage process, the first stage including adding 0-3.0% of the activating agent and 0.05-1.0% of the polymer, by weight, and in a second stage adding 0-5.0% of the activating agent 0.3-5% of the polymer, by weight, to the mixture of the first stage, wherein at least a part of the polymer is added as a dry solid and the water in the first stage is at least 20% by weight and at most 50% by weight in the second stage.

主权项

1. A method for producing a modified smectite or smectite-containing substance capable of forming a gel with a stable cross-linked structure and capable of taking up and releasing water in a reversible manner, comprising:
treating a crude non-activated smectite or smectite-containing substance having a water content of at least 13% by weight with a water soluble activating agent and with a water soluble polymer capable of reacting with said smectite or smectite-containing substance, wherein in a first stage 0.17% to 3.0% by weight, calculated on the weight of the smectite or smectite-containing substance, of the water soluble activating agent and 0.05-1.0% by weight, calculated on the weight of the smectite or smectite-containing substance, of the water soluble polymer are admixed with the non-activated smectite or smectite-containing substance, wherein at least part of the polymer and the activating agent are added as an aqueous solution or become in a dissolved state during mixing because of the high water content in the crude smectite or smectite-containing substance, thereafter in a second stage 0-5.0% by weight, calculated on the weight of the smectite or smectite-containing substance, of the water soluble activating agent and 0.3-5% by weight, calculated on the weight of the smectite or smectite-containing substance, of the water soluble polymer are admixed with the mixture obtained in the first stage, wherein at least a part of said water soluble polymer is added as a dry solid, wherein the water content in the first stage is greater than 20% by weight and the water content in the second stage ranges from greater than 20% by weight to at most 50% by weight, on the basis of the mixture, which amount of water is insufficient for forming the final cross-linked structure, and in the mixture obtained at least 10% by weight, calculated on the total polymer binding capacity of the smectite or smectite-containing substance, of the polymer is bound with the smectite or smectite-containing substance producing a smectite or smectite-containing organic compound and at least 15% by weight, calculated on the total polymer binding capacity of the smectite or smectite-containing substance, of the polymers is in free form not bound with the smectite or smectite-containing substance.