Polyurethane rigid foam foaming process
Divided into the following three types:
First, the prepolymer method
The prepolymer foaming process is to prepare (white material) and (black material) into a prepolymer, and then add water, a catalyst, a surfactant, other additives, etc. in the prepolymer to be mixed under high speed stirring. Soak, after curing, it can be matured at a certain temperature.
Second, semi-prepolymer method
The foaming process of the semi-prepolymer method is to first form a part of the polyether polyol (white material) and the diisocyanate (black material) into a prepolymer, and then another part of the polyether or polyester polyol and the diisocyanate, water. A catalyst, a surfactant, other additives, and the like are added, and the mixture is foamed under high-speed stirring.
Third, one-step foaming process
The polyether or polyester polyol (white material) and polyisocyanate (black material), water, catalyst, surfactant, foaming agent, other additives and the like are added in one step, mixed under high-speed stirring, and then foamed.
The one-step foaming process is currently widely used. There is also a manual foaming method, which is the easiest way to accurately weigh all the raw materials, put them in a container, and then immediately mix them evenly into the mold or the space where the foam needs to be filled. Note: The polyisocyanate (black) must be weighed in the final weighing.
The polyurethane rigid foam is generally foamed at room temperature, and the molding process is relatively simple. According to the degree of construction mechanization, it can be divided into manual foaming and mechanical foaming; according to the pressure during foaming, it can be divided into high pressure foaming and low pressure foaming; according to the molding method, it can be divided into casting foaming and spray foaming.
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