Polymer foam is braced by the release of timely processing of the gas to form a porous polymer material of a class of additives, according to the mechanism of gas formation is divided into physical blowing agents and chemical blowing agents.

Physical blowing agents
More types of physical blowing agents, traditionally mainly CFC compounds CFCS, as will destroy the ozone layer, ten years have been seeking and the development of domestic alternative to the ideal, and has basically three kinds of solutions. Currently, PU soft foam production mainly HCFC-141b, HCFC-22 as a transitional product, but a better alternative substances and should be HFC-245fa HFC-365mfc.

Chemical blowing agent
As chemical blowing agent used many different types of material, such as N-nitrosourea compounds, azo compounds, hydrazide compounds, are mainly varieties of azodicarbonamide blowing agent (ADC), foaming agent DPT, OBSH etc. , which accounts for the chemical blowing agent ADC abroad 90% of consumption in China accounted for more than 95%. The following will focus on the application of ADC blowing agent and the modification of progress.

ADC foaming agent
China is the world's largest producer and supplier of ADC, the annual production capacity of 150,000 tons, about the world's total production of nearly 50%, from 1995 to 2003 average annual growth rate of about 18% capacity, the manufacturer about 30 are more than 30 provinces and cities across the country, including Jiangsu Sopo Group, Zhejiang Juhua Group, Jiangxi Electrochemical Factory, Ningxia Hydro-ton annual capacity has reached the level; production equipment has many improvements, such as sodium hypochlorite production equipment, large-scale, continuous; condensation tank, large scale oxidation reactor; switch to continuous drying process and so on.

Blowing agent OBSH
Blowing agent OBSH is commonly used in plastics and rubber industry low foaming, mainly by reaction with hydrazine hydrate, after ether sulfonate derived from the advantage of lower decomposition temperature, decomposition does not require additional additives, for a variety of synthetic materials ; very low toxicity, suitable for contact with food packaging materials; electrical insulation properties; have the dual role of curing agent and blowing agent; fine uniform foam. First developed by Japan, the use of wires and cables in the field of UHF are popular and widely used. Now has developed a variety of foreign OBSH modified series products, such as Japan Yonghe into the N # 3000,5000,100 S, 100M and other OBSH modified products. China also OBSH for research and development, the current Shanxi Chemical Industry Research Institute, Hangzhou Haihong companies built small-scale production plant. However, due to its relatively high prices, has limited application.