Compound modification method for clay

The invention relates to a compound modification method for clay, which comprises the following steps: dissolving 0.5-2g of silane coupling agent in a certain amount of alcohol-water mixture, and stirring for a certain time on a magnetic stirrer; adding a certain amount of clay into a stirring furnace, performing high-speed stirring at a certain temperature, and meanwhile, adding the alcohol-water mixture into the clay within a certain time; after the alcohol-water mixture is added, continuing to stir for 0.5 hour, pouring out, and performing heat treatment at 80-200 DEG C for 1-3 hours; and mixing the product obtained in the previous step with a certain amount of long-chain alkyl ammonium salt water solution, adding a small amount of acetic acid to regulate the pH value to 2-5, stirring at a certain temperature for a certain time, repeatedly performing vacuum filtration 2-5 times, and performing heat treatment at 80-200 DEG C for 2-5 hours. Secondary modification takes full advantages of the synergic modification effects of the silane coupling agent and the long-chain alkyl ammonium salt, enlarges the molecular layer interval of the clay, increases the affinity of the clay to polymer and widens the application range of the clay.