The
China board trading network news:
About the choice of polyurethane sheet raw materials:
The isocyanate (PAPI) component used was Yantai Wanhua PM-200. This component was fixed. As the amount of PAPI increases, the degree of cross-linking of the foam increases, and its strength and stiffness also increase. However, if the amount of PAPI is too much, the foam will be brittle and the core material will crack easily.
The first choice of polyether polyol is the most important one. Polyether polyol is one of the basic raw materials that make up polyurethane rigid foam. It affects the physical and mechanical properties, dimensional stability and foaming process performance of the foam core material. After the polyether type was determined based on the initiator, hydroxyl value and viscosity, the content of potassium ion in the polyether was selected to be low.
Foam stabilizers have good emulsifying power. The main control cell size, to maintain the stability of the cell, to prevent cell collapse. The organosilicone foam stabilizer has a good effect on this, and its amount can be adjusted within 1.5 to 2.5 (mass fraction). The type and amount of the foaming agent have a direct influence on the physical properties such as the density and strength of the polyurethane rigid foam. .
The foaming agent not only can adjust and control the density and performance of the foamed product, but also can reduce the viscosity of the combined polyether, improve its foaming process, increase the flowability of the foam, and facilitate foam molding. In view of the need for sustainable development strategies, the use of alternative foaming agents has now been restricted to the use of CFC-based fluorocarbon compounds that have severely damaged the ecological environment.
The catalyst can be selected to delay the catalytic system, so that milking time and gel time interval is longer, effectively improve the fluidity of the foaming system, improve the foam performance, suitable for the production process operation. The factors such as whether the foam is even in the cavity, the degree of fine foam, and the closed cell porosity have a great influence on the overall thermal insulation performance of the sheet. These factors are related to the firm adhesion of the foam to the cavity wall, the dimensional stability of the foam and the like.
The flame retardant can improve the fire resistance of the foam, but the flame retardant has a destructive effect on the foam during the foaming process. Under the premise of ensuring the improvement of the flame retardant effect, the use performance and the dimensional stability of the foam are ensured.
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