Patent ID: 8846796

Claim:
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.