Matters needing attention in casting and molding of polyurethane rigid foam

As the main auxiliary agent for polyurethane foaming, color paste is widely used in various polyurethane materials. As a professional polyurethane color paste manufacturer in East China, the color paste produced by our factory has the characteristics of high color concentration, good fluidity, bright color and strong weather resistance without affecting foaming when added in large quantities. ......

Amine catalyst is the main catalyst for casting foam molding. Delayed amine catalyst can be used to prolong the opalescence time and meet the requirements of mold filling. This kind of catalyst can improve the fluidity of raw material system without affecting its curing. The isocyanate index is slightly higher than 100, such as 105.

In the process of pouring foam molding, raw material temperature and ambient temperature directly affect the quality of foamed plastic products. The appropriate ambient temperature is 20 ~ 30℃, and the raw material temperature can be controlled at 20 ~ 30℃ or slightly higher. It is difficult to obtain high-quality products if the temperature is too high or too low.

For large-scale products such as ships and vehicles, it is difficult to control the ambient temperature, so the raw material temperature can be properly controlled and the amount of catalyst can be adjusted; 79— The requirements for the mold are reasonable structure, convenient disassembly, light weight, pressure resistance and good smoothness of the inner surface. At the same time, according to the size and different shapes of the mold, multiple exhaust holes should be drilled at appropriate positions.

The mold is usually made of aluminum alloy, and sometimes steel mold is used. The mold temperature directly affects the removal speed of reaction heat. The mold temperature is low, the foaming ratio is small, the product density is high, and the skin is thick. High mold temperature is the opposite. In order to make high-quality foamed plastic products, the mold temperature is generally controlled in the range of 40 ~ 50℃. When the material temperature and mold temperature are low, the chemical reaction is slow and the foam curing time is long. The higher the temperature, the shorter the curing time. When the foam is injected into the mold, the mold and the product should be cured together in a higher temperature environment before demoulding, so that the chemical reaction can be completed. If the mold is demoulded too early, the curing will be insufficient and the foam will be deformed.

Different kinds of raw materials and shapes and sizes of parts require different curing time and temperature. Generally, molded foam needs to be cured for 10min before it can be demoulded. Because of the short mixing time, mixing efficiency is a factor that should be paid attention to.

Hand-poured foam, the agitator should have enough power and speed, mix evenly, the foam hole is fine and uniform, and the quality is good; Poor mixing, coarse and uneven cells, and even the phenomenon that the chemical composition does not meet the requirements of the formula in a local range, which greatly affects the quality of products.

The above are some of my suggestions. If there is anything wrong, please leave a message below and share with us. Thank you!

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