Selection of raw materials for polyurethane sheet
Selection of raw materials for polyurethane sheet:
The isocyanate (PAPI) component is typically sourced from Yantai Wanhua PM-200, and this component is fixed. As the amount of PAPI increases, the cross-linking density of the foam improves, leading to higher strength and rigidity. However, excessive PAPI can make the foam brittle, increasing the risk of cracks in the core material.
The choice of polyether polyol is crucial. It is one of the fundamental ingredients in rigid polyurethane foam, directly influencing the mechanical properties, dimensional stability, and foaming process. After selecting the appropriate polyether based on factors like initiator type, hydroxyl value, and viscosity, it's important to choose a low potassium ion content to ensure better performance and stability.
A high-performance foam stabilizer is preferred, as it helps control cell size, maintain cell structure, and prevent collapse. Silicone-based foam stabilizers are particularly effective in this regard. The foaming agent is usually used in a range of 1.5 to 2.5% by mass, which directly affects properties such as density and strength of the rigid foam.
Blowing agents not only help regulate the density and performance of the final product but also reduce the viscosity of the polyether mixture, improving the foaming process and enhancing the fluidity of the foam, making it easier to mold. With sustainability becoming a key focus, the use of environmentally harmful CFCs has been largely restricted, and alternatives are now being widely adopted.
Catalysts play an essential role in controlling the reaction speed. A delayed catalytic system is often used to extend the time between whitening and gelation, improving the fluidity of the system and ensuring better foaming performance that aligns with production requirements. Factors like uniform cell distribution, foaming degree, and foam closure significantly impact the thermal insulation performance of the panel. These are closely related to how well the foam adheres to the cavity walls and its dimensional stability during the process.
Flame retardants enhance the fire resistance of the foam, but they can also negatively affect the foam structure during the foaming process. Therefore, it's essential to balance flame resistance with maintaining the foam’s performance and dimensional stability after curing.
Various inorganic pigment choice with iron oxide powder form is used for concrete or cement. With different color type and fineness, it is suitable for all kinds of construction use.
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