Initiators are generally compounds with weak bonds that easily decompose into active species, where covalent bonds can undergo both homolytic and heterolytic cleavage. They are also known as starters. In the fields of chemistry, chemical engineering, medicine, and petroleum, the common Chinese translation of the English term 'initiator' is (tēnxiān jì).
An initiator is a substance that can initiate a polymerization reaction of monomers. The active centers for unsaturated monomer polymerization include free radicals, anionic compounds, cationic compounds, and coordination compounds. In the adhesive industry, the free radical type is the most widely used. It exhibits unique chemical activity, undergoing homolytic cleavage of covalent bonds under the influence of heat or light to generate two free radicals, which can initiate a polymerization reaction. Initiators have wide applications in the synthesis of polymer materials such as plastics, rubber, and coatings.
Initiators play a significant role in the research and production of adhesives and sealants. The solvent polymerization of acrylates to prepare pressure-sensitive adhesives, the solvent polymerization of vinyl acetate to manufacture building adhesives and sealants, the synthesis of styrene-acrylic emulsions, ethylene-propylene emulsions, VAE emulsions, styrene-butadiene latex, chloroprene latex, white glue, etc., the grafting of chloroprene adhesives, SBS grafted adhesives, the crosslinking and curing of unsaturated polyester resins, the curing of anaerobic adhesives, and the curing of fast-curing acrylate structural adhesives all require initiators. Initiators directly affect whether the polymerization reaction proceeds smoothly, the polymerization rate, and the shelf life of the product.
