Study On The Preparation Of Foaming Agent ADC By Oxidizing Hydrogen Peroxide And The Industrialization

Azodicarbonamide （ADC）, which chemical structure formula isH2NCONNCONH2, is an important foaming agent with high efficiency and is widelyused in general purpose. It has lots of advantages，such as higher gas-makingcapacity, bubble distribution. Its decomposition product has four advantages:non-toxicity, non-smell, non-supporting combustion, non-pollution. It can be used asthe foaming agent for PVC, PE, PP, polyamide, chloroprene rubber adhesive, butylrubber, butyl benzene rubber, silicone rubber and so on. In addition, it is suitable fornormal pressure foaming processing and foaming processing with pressure. Theprocess with chlorine gas and sodium chlorate as oxidant is still applied widely inADC production. But both of the two processes has many disadvantages, such ashigh energy consumption, high costs, severe contamination and so on. Hydrogenperoxide oxidation process is a new method to produce ADC foaming agent. With thismethod, the only by-product is water, no pollutants. The dosage of the H2O2is easy tocontrol. Then the problem to control the dosage of the oxidant is solved. The producthas stable quality and yield. So, the method has a lot of advantages, such as nopollutants, no danger of explosion, no by-products, high product quality, high yield,higher gas-making capacity and so on.The industrial process is achieved through theoretical research, laboratoryresearch and pilot test. Under the use of iron-based chemical compound as thepromoter, the suitable technological condition of laboratory research is as follows: theinitial solid-liquid ratio1:2.5, The molar ratio of the initial raw mixture(biurea：hydrogen peroxide)1:1.05, the catalyst concentration1.75g/l, the promotersconcentration3.0g/l, the acidities is3.5mol/l, the reaction temperature50℃, and thereaction yield is97.44%with the product purity above98.88%. After the theoreticalresearch, the reaction mechanism is given, and the mass transfer rate between solid and liquid is the rate controlling step. Through the pilot test, the results showedthat the mother liquor can be recycled straight without treatment. The suitable rangeof technological condition is as follows: the initial solid-liquid ratio1:2.5, The molarratio of the initial raw mixture(biurea：hydrogen peroxide)1:1.05, the catalystconcentration1.65g/l~1.85g/l, the promoters concentration2.8g/l~3.2g/l, theacidities is3.3mol/l~3.7mol/l, the reaction temperature48℃~52℃, then thereaction yield is up to95.14%with the product purity above97.25%. With recyclingmother liquor, the suitable range of technological condition in the industrial process isas follows: the reaction time is6h, the product yield is up to92.51%, the productpurity above96.23%, the blowing value211ml/g,38μm residue on sieve to0.15wt%,the decomposition temperature203℃,the heating loss less than0.21%, thecontent of ash less than0.03%. The quality indexes of the product meet therequirements of first grade ADC of Chinese national quality standard.The new method has lots of advantages, such as low energy consumption, lowcosts, slight contamination and high profits. The technology is in a leading position inour country and is a valuable technology to be developed and applied.