Pigment concentrates for the production of
Automotive paints (putty and primer)
Flexographic and gravure inks
Wood and furniture coatings
Recommended additions for the above applications are 5.0-30.0% for inorganic pigments, 20-70% for organic pigments, 40-120% for carbon black, and 0.5-2.0% for co-ground
Persulfate sulfite initiation system Persulfate-sulfite initiation system is widely used. Commonly used reducing agents include sulfite, formaldehyde bisulfite (white powder), thiosulfate, and dithionite Salt, nitrite, mercaptan, etc. Redox reaction between them and persulfate.
S, O+H SO, —SO+SO 7·+H SO, ·(4-28)
seO j-+S gO-SO; -+SO, ·+S, O, ·(4-29)
S: Ol-+RS HHS OT+SOT·+RS·(4-30)
The characteristic of this system is that one molecule of peroxide generates two free radicals (other redox initiation systems generate one free radical), and the initiation efficiency is high. However, molecular polyethylene wax if the two primary free radicals cannot diffuse rapidly, there is still the possibility of coupling termination. . The generated primary free radicals are easily destroyed by the action of gas, so inert gas must be used to block oxygen in the polymerization reaction, especially in the initial stage of the reaction.
Because the system reacts to form sulfuric acid, the pH value of the system can be significantly reduced, and a buffer is often added during polymerization. This initiation system is commonly used in styrene butadiene emulsion polymerization, vinyl acetate emulsion polymerization, acrylate emulsion polymerization, and multi-emulsion copolymerization of acrylate and styrene.
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