The Structure and Use of Polyurethane

The structure and use of polyurethane
Polyurethane rigid foam foaming process
Divided into the following three types:
1. Prepolymer method
The foaming process of prepolymer method is to make (white material) and (black material) into prepolymer first, and then add water, catalyst, surfactant, and other additives to the prepolymer and mix under high-speed agitation. Foam, cure at a certain temperature after curing.
2. the semi-prepolymer method
The foaming process of the semi-prepolymer method is to make a part of polyether polyol (white material) and diisocyanate (black material) into a prepolymer, and then combine another part of polyether or polyester polyol with diisocyanate, water , Catalysts, surfactants, and other additives are added and mixed under high-speed stirring for foaming.
3. one-step foaming process
Add polyether or polyester polyol (white material) and polyisocyanate (black material), water, catalyst, surfactant, blowing agent, other additives and other raw materials in one step, and mix under high-speed stirring and then foam.
The one-step foaming process is currently commonly used. There is also the manual foaming method, which is the easiest method. After all the raw materials are accurately weighed, they are placed in a container, and then the raw materials are mixed uniformly and injected into the mold or the space that needs to be filled with foam. Note: When weighing, the polyisocyanate (black material) must be weighed in last.

Rigid polyurethane 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 foaming pressure, it can be divided into high-pressure foaming and low-pressure foaming; according to the molding method, it can be divided into pouring foaming and spraying foaming.