Self-hardening furan resin sand casting process Why phosphoric acid is mostly used as a curing agent for high nitrogen furan self-hardening resins, but seldom used as a curing agent for low nitrogen furan self-hardening resins? This is because low nitrogen and high furfuryl alcohol resin, when acid is used as curing agent, the hardening speed is slow, the demolding time is long, and the strength is very low. The high nitrogen low furfuryl alcohol resin uses phosphoric acid as the curing agent to obtain the required curing speed. In addition, the high nitrogen low furfuryl alcohol resin uses phosphoric acid as a catalyst to obtain good final strength. The reason for this result is mainly due to the poor miscibility of phosphoric acid and furfuryl alcohol and high affinity with water, which makes it difficult for the water contained in the resin and the catalyst and the water produced in the resin polycondensation reaction to diffuse. And discharged, with phosphoric acid as the core. Water droplets remain in the resin film and destroy the compactness of the resin film, so the strength is low. The high nitrogen resin has good mutual solubility with water, and various waters are not easy to be concentrated into droplets with phosphoric acid as the core. The resin film has a good structure and high strength.
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