Synthesis and Properties of Mixed Physical Extinction Polyester
In the application of powder coatings, low light powder coatings have great applications, occupy a large proportion of the powder coating product structure. There are two main ways of extinction of powder coating: physical system and chemical system. Physical extinction system generally matting filler, wax-type matting agent, non-wax type matting agent to achieve. The chemical extinction system can be adjusted by the amount of resin, curing agent and extinction curing agent. The project uses a physical extinction system to synthesize a 6: 4 mixed resin TS6700 for indoor use. The extinction powder coating material is obtained through efficient mixing with a physical matting agent to make a powder coating.
1, polyester resin synthesis
The raw material diol, dibasic acid and other reaction materials according to formula amount into the reactor, filled with nitrogen protection, when the temperature was raised to 190 ℃, began to esterify water, continue to heat up to 255 ℃, the reaction without esterification of water , A colorless and transparent resin was obtained. The polyacid capping agent was added and the reaction was incubated at 255 ° C for 90 minutes. After the completion of the reaction, evacuation to (-0.095 Mpa) was gradually carried out and the reaction was carried out under a vacuum at 255 ° C for 60 minutes. Cooling to 200 ℃, the reaction is completed, the material.
2, low light powder coating sample preparation
The trial-made polyester resin, physical matting agent, pigment, filler, leveling agent, etc. according to the amount of formula added to the ingredients in the container, stir well, the extruder melt extrusion, crushing, to obtain a powder coating, electrostatic spraying On the template, place it in a curing oven to cure the coating.
3, physical and chemical properties of polyester resin index
Appearance: Colorless or light yellow transparent particles; Acid value: 48.0 ~ 56.0mgKOH / g; Melt viscosity (180 ℃): 1000 ~ 3000CP; Glass transition temperature (Tg) 58.5 ℃; Softening point (Tf) 115 ° C.
The performance requirements of low-gloss powder coatings mainly include the leveling and fineness of the coating film, the gloss and scratch resistance of the coating film, and the leveling, smoothness and gloss of the coating film are the most concerned issues of the low-gloss finish coating. Low-gloss powder coating film gloss and leveling and base materials, fillers, matting agents and so have an impact on the polyester resin, to improve the leveling of low-light powder coatings to reduce the gloss of the powder from the polyester resin Viscosity, and end-group activity to achieve two. Reduce the viscosity of polyester resin, coating unit to increase the level of cure curing area, so as to achieve a good leveling purposes. The combination of end-capping agent to adjust the terminal activity, and matting agent mixing process, that can play the role of extinction, and the coating does not cure too fast, resulting in coating flow worse.