The Preparation Study Of Organobentonite For Food Contact Materials

In recent years, how to improve the barrier and mechanics performance of food packingmaterial received much attention from the packaging world. In the experiment, to better enhancethe performance of packaging material, the sodium bentonite and organobentonite were preparedand compound with packing material at the same time, to prepare food packaging material whichhas good performance.The raw material used in the experiment was calcium bentonite with low quality, which wasfrom a mine in Wei Fang. In the experiment, the sodium salt was used as sodium modificationagent and the wet processing, aging processing and secondary centrifugal purification processingwere also used to prepare the high purity of sodium bentonite. And the long-chain quaternaryammonium salt was used as organic modifying agent, the acid activation processing and wetprocessing was used to prepare the organobentonite. AFS, AAS, XRD, XRF, IR and SEM wereused to analyze and characterize the preparation of sodium bentonite and organobentonite. In theexperiment, the sodium bentonite and organobentonite were composite with polypropylene,respectively, and the tensile strength test and blocking test were performed for the material ofpolypropylene/bentonite composites.The results of the experiment showed that the good quality of sodium bentonite could be getunder the condition of3%NaF as the sodium modification agent, solid-liquid ratio was1:4,temperature was60℃and the reaction time was60min. After aging processing, the sodiumbentonite was performed by secondary refining centrifugal in the speed of4000r/min,solid-liquid ratio1:30and centrifugal4min, and the montmorillonite content of the sodiumbentonite was as high as94%, which safety performance in line with the national drug standardof montmorillonite and could be used in food packaging materials. The sodium bentonite wasacid activation and with40%octadecyl trimethyl ammonium chloride added as the organicmodifying agent, under the condition of solid-liquid ratio1:30, temperature80℃, reaction90min,and the organobentonite was taken, which was floating on the water surface. And after thesuction filtration, washing and drying the organobentonite which viscosity was as high as1.5P·scould be prepared. The pressed film was performed after mixing and heating composite thepolypropylene with organobentonite, the tensile strength, oxygen transmission rate and moisture permeability of the polypropylene/organobentonite composite material were improvedsignificantly.A small amount of tannic acid was added in the aging processing, the acid activationprocessing and washing processing was adopt in the preparation of organic modified, which washelpful to remove the harmful substances in the bentonite raw ore. The technology of themodification of sodium bentonite and organic modification was improved in this experiment, andmade the preparation of organobentonite without use of the drying dehydration processing whichneede more energy. Eventually, the organobentonite was composite with polypropylene in foodpackaging materials, and the barrier and mechanics performance of the food packing materialwere improved greatly after the composite.