Rare earth phenolic resin improves coating performance

Phenolic modified epoxy powder coating, due to the copolymerization and cross-linking reaction of the two resins, increases the cross-linking density of the system, improves the resistance of the coating to media penetration, especially the resistance to acidity, water resistance and organic solvents, etc. This lack of epoxy resin. After adding rare earth phenolic modified epoxy powder coating, the mechanical properties of the coating have been significantly improved compared with the phenolic modification alone. The phenolic brittleness has been greatly improved, and the boiling water resistance, water absorption, and organic solvent resistance have been further improved. Coating resistance to media penetration and storage stability of powder coatings can be greatly improved. According to experts, since rare earth elements are generally easy to lose three electrons, they are positively valenced and have a very high reactivity. They are high-activity agents that participate in the reaction, and are also self-catalysts; and the compound bonds obtained after reaction with the resin are extremely strong, so the resin Heat resistance, wear resistance, corrosion resistance and other properties are improved. College of Materials Science and Engineering, Beijing University of Chemical Technology, recently modified epoxies epoxy powder coatings, using chlorinated rare earth to modify phenolic resins, using rare earth modified phenolic resins, the advantages of good mechanical properties, to make up for the lack of phenolic resin .

On the preparation method of rare earth phenolic resin, according to experts, take a certain amount of phenolic resin added 5% chlorinated rare earth, down 500mL three bottle, heat up and start stirring 10 ~ 15min, heated to 80 ~ 85 °C heat preservation reaction 10 ~ 15min Then, the reaction solution was heated to boiling, and the reaction was refluxed for 3 to 4 hours under boiling conditions. Heating and vacuum dehydration were continued. The temperature rise rate of the system was observed. When the temperature reached 140°C to 160°C, the material could be discharged according to performance requirements. RPC modified phenolic resins GPC and IR tests showed that the three characteristic peaks related to phenolic hydroxyl groups in the infrared spectrum of the modified phenolic resin were 3318cm-1, 1362cm-1 and 1233cm-1, and the vibration intensity ratio was unchanged. The decrease in sexual activity indicates that rare earth elements react with phenolic resins to form bonds with strong bonds. The peak molecular weight Mp of the unmodified phenolic resin was 488. After modification, the peak molecular mass Mp of the phenolic resin increased to 605, and the Mn of the high molecular mass fraction peak increased from 683 to 709 due to the rare earth. The copolymerization of elements with phenolic resin molecules results in an overall increase in the number average molecular mass Mn. Both the IR and GPc spectra demonstrated that the rare earth chloride particles form chemical bonds with the phenolic moieties and the rare earth modified phenolic was chemically modified. The mechanical properties of the coatings after rare earth addition were significantly higher than that of phenolic modification, and the water absorption and boiling water resistance of the coatings were further improved, which also indicated that the properties of the powder coatings after rare earth modification had been significantly improved.

After phenolic modification, the acid resistance of the system is greatly improved, and the resistance to organic solvents is also significantly improved. The effect of modified rare earth phenolic is more obvious. Experts also described the storage stability of rare earth phenolic modified epoxy powder coatings. The storage stability of dicyandiamide-cured powder coatings is general. After the introduction of the curing accelerator 2-methylimidazole, the stability of the system is worse due to the strong activity of the accelerator. Generally, the agglomerates are stored for less than one week, and the coating Reactivity decreased. Under normal circumstances, most of the accelerators were selected to be modified with acrylate to improve their pot life. In this study, the rare earth phenolic modification method was used, because the resulting compound after the rare earth reaction is very stable, and it is known to be PVC. With the most ideal stabilizers at present, the stability of modified powder coatings has greatly increased. The specific method used was to seal the powder coating sample and store it at room temperature for 6 months. After removal, the sample was compared with the fresh sample. The appearance of the coating was not changed before and after storage, and then the DSC test was performed. From the experimental chart, it can be seen that except for the characteristic peak of the epoxy bond at 913CM-1, which is lower than that stored when it is not stored, the other peaks such as the 3429 cm-1 hydroxyl peak, the dicyandiamide peak at 2206.9 cm-1 and 2162.2 cm-1. There were no major changes in the reactive groups, indicating that they were unreacted. The curing reaction of the powder coating after 6 months of storage was found to be still operable, and the curing performance had no significant effect.