Development of vinyl resin technology (middle)

3. Thickening vinyl ester resin

As a high-performance unsaturated resin, the thickening property of vinyl resin has always been the direction of research by various manufacturers. This is because the unique application characteristics of BMC/SMC have been recognized by customers, especially with BMC/SMC in automotive zero. For component applications, thickened vinyl resins can withstand higher impact forces than general purpose unsaturated resins and have good creep and fatigue resistance. These components include wheels, seats, heat sinks, grid plates, engine valve sleeves, and more. Of course, thickened vinyl resins can be widely used in electrical insulation, industrial pump valves, golf clubs, and the like.

As a thickening vinyl resin, it is naturally required that the resin has the following characteristics: (1) good wettability with reinforcing materials and fillers; (2) initial low viscosity and fast thickening characteristics; (3) good mechanics Characteristics, including toughness and fatigue resistance; (4) longer storage period; (5) lower curing exotherm and lower styrene volatilization. In order to achieve the effect of use, in the synthesis of vinyl resins, the most common method is to introduce acidic functional groups (carboxylic acids) on the vinyl ester molecules, and then use these carboxyl groups with alkaline earth metal oxides (such as magnesium oxide, oxidation). Calcium, etc.), but this method takes a long time to thicken and generally takes several days, which is sensitive to water content. Therefore, another method has been developed in which a polyisocyanate and a polyol are reacted to produce a network structure, thereby achieving rapid thickening of the resin. The method is suitable for low pressure molding, and has viscosity control stability and temperature resistance. The characteristics of low humidity requirement, long storage period, and high interlayer bonding strength of the product, and low acid value resin with excess alcohol can also be used as a thickener.

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4. High temperature resistant vinyl resin

The molecular skeleton of the vinyl resin is an epoxy resin. When a novolac epoxy resin is used as a raw material, the synthesized NOVOLAC type new grade vinyl resin has good corrosion resistance, solvent resistance, and high temperature resistance. Our phenolic epoxy vinyl ester resins from well-known domestic and foreign manufacturers have been tested according to the relevant national standards of China. The results show that the heat distortion temperature (HDT) of these resins is between 132 and 137 ° C, while the phenolic rings of some domestic manufacturers. The oxyethylene resin has a lower heat distortion temperature, which is lower than 125 °C. However, in some industrial practice applications, the heat resistance of the resin has been put forward higher, and the heat distortion temperature of the high cross-linking density vinyl resin 898 provided by a few domestic and foreign manufacturers such as Shanghai Fuchen in the early 21st century can be Above 150 ° C, the molecular structure of this type of resin has been modified to optimize the heat resistance of the resin, and the styrene content has been adjusted to meet the practical requirements. Compared with the conventional phenolic epoxy vinyl resin, it has higher temperature resistance and can be used for a long time in a strong corrosive environment of 200 ° C gas phase. At the same time, our experience shows that vinyl resin for heat-transfer paint can withstand 300 ° C in 2-3 min. Temperature shock, this unique application is in insulation applications and can fully reach Class C insulation.

This type of resin can be widely used in high temperature applications such as smelting and power desulfurization (FGD) equipment, such as cooling towers, chimneys and chemical pipelines. At the same time, this type of resin also has the characteristics of strong solvent resistance and strong oxidizing medium.