What's the common problems and solutions for polyurethane prepolymer processing?
If the polyurethane prepolymer is not processed according to the correct process and method during processing, various problems will occur that affect the performance of the product. Today, the editor will talk about common problems and solutions during the processing of cast polyurethane prepolymer.
1. Product hardness is low
The ratio of curing agent to prepolymer is unbalanced, the post-curing time is insufficient, the product temperature is high during the test, and the test surface is uneven.
2. Long gel time
The ratio of curing agent and prepolymer is out of balance, the material temperature is moderate and the mold temperature is low.
3. Product transparency and hardness are low
Long-term or repeated heating of the prepolymer, low amounts of added curing agent, different operating temperatures, and hygroscopicity between the curing agent and the prepolymer.
4. The product surface is defective
The mold is not cleaned thoroughly, the temperature difference between the prepolymer and the mold is large, and the pouring method is improper.
5. The product has many bubbles
The curing agent and prepolymer are hygroscopic, the pouring method is improper, the raw materials defoaming is incomplete, the curing agent, color paste, etc. contain too much water and are mixed improperly.
6. Product shrinkage is high
The ratio of curing agent and prepolymer is unbalanced, the temperature difference between the prepolymer and the mold is large, and the temperature difference between the product and the storage environment is large.