The commonly used catalysts for powder coatings are quaternary ammonium salts, quaternary phosphonium salts, imidazole and its derivatives, organometallic complexes, acid or amine enclosed sulfonic acid, etc. The first three types of catalysts are more commonly used. The first three types of catalysts are used more often. The addition amount is within 5 thousandths of the total formula.
In addition to the above-mentioned auxiliary products, phosphate ester monomers have special functional phosphate ester monomers, which can be used for resin modification to give the resin base material a phosphoric acid functional group, which can firmly connect the coating base material to the base material in the form of covalent bonds Metal substrates include aluminum and various cold-rolled steel, zinc steel, phosphated steel, galvanized steel and stainless steel .
Supply and sales manufacturers: Ad her an tAP B [Deqian (Shanghai) Chemical Co., Ltd.], byk ptfe wax Lubrizol (The Lubrizol Corporation), Add it ol (Hoechst). Four. Chlorinated polyolefin
The development of the petrochemical industry and the popularity of light, small, and individualized coatings have made it more common for coatings to be used on plastic substrates. There are many types of plastics, including polyethylene, polypropylene, thermoplastic polyolefin, ABS, nylon, and PVC. Among them, polypropylene and thermoplastic polyolefins (such as PP/EPDM) are widely used in the automotive industry, toys, household appliances and other components due to their low price, light weight, high strength, and toughness. Generally, the following complete procedures are included before plastic coating: cleaning with a cleaning solution, then cleaning with deionized water, drying, and finally wiping with a volatile solvent. When the surface is uneven or the cavities are serious, the primer can be used for filling and leveling. Due to the low polarity of plastics, it is easy to cause electrostatic dust collection. Therefore, before painting, it is necessary to use electron-removing air or anti-static liquid to carry out electrostatic dust removal of the substrate to improve the adhesion of the paint.
The surface polymerization of polypropylene and thermoplastic polyolefins (such as PP/EPDM) has high crystallinity, low polarity and low surface energy. General coatings cannot be directly coated to obtain good adhesion. Therefore, they must be applied before coating or printing. Surface treatment to obtain good adhesion, there are several common treatment methods.
Compare the pollutants of the four general plastic surface treatment methods, and then proceed | the way the material forms free radicals. Polished by the treatment method
Corona treatment (CDT)
Clean the surface first to remove the sanding, increase the contact surface area, and improve the overall bond strength
Make plastic under high voltage discharge
The surface of reactive groups increases the surface energy of surface activation treatment of plastic parts
Burn and oxidize the plastic sheet by flame
Carry out ionization treatment under vacuum to oxidize the surface and increase the surface energy
Lower cost than CDT simple mouth
High reproducibility and high cost
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