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Polyurethane sheet has the following characteristics:
Stability: Light weight, high strength, good dimensional stability. We produce intermittent panels, and the rigid polyurethane foam is tested for foam performance after one week of aging.
Strong adhesion: Polyurethane rigid foam has good adhesion strength to metals such as steel, aluminum, stainless steel, wood, concrete, asbestos, asphalt, paper, and most plastic materials such as polyethylene and polypropylene. The size of the bonding strength between the foam and the face material directly affects the practical effect of the composite board.
Superior thermal insulation performance: polyurethane rigid foam has high closed cell rate and extremely low thermal conductivity, so polyurethane rigid foam has the best thermal insulation performance among current building materials. The data shows that the use of polyurethane sandwich panels can save 60% of the heating cost of the operation compared to the external wall without thermal insulation. Taking the composite of steel plate and rigid polyurethane foam as an example, the thermal conductivity of the composite panel is listed in the table below.
Selection of raw materials for polyurethane sheet:
The isocyanate (PAPI) component is selected from Yantai Wanhua PM-200, which is fixed. As the amount of PAPI increases, the degree of cross-linking of the foam increases, and its strength and stiffness also increase, but if the amount of PAPI is too much, the foam will become brittle, and the core material is prone to cracks.
First of all, it is most important to choose polyether polyol. Polyether polyol is one of the basic raw materials for composing polyurethane rigid foam. It affects the physical and mechanical properties, dimensional stability and foaming process performance of the foam core. After the polyether type is determined according to the initiator, hydroxyl value and viscosity, the content of potassium ions in the polyether is selected to be low.
It is advisable to choose the foam stabilizer with strong emulsifying ability. It mainly controls the size of the cell, maintains the stability of the cell, and prevents the cell from collapsing. The silicone foam stabilizer has a good effect on this, and its dosage can be adjusted within 1.5 to 2.5 (mass fraction) The type and dosage of the foaming agent have a direct impact on the physical properties such as the density and strength of the polyurethane rigid foam. .
The foaming agent can not only adjust and control the density and performance of the foam product, but also reduce the viscosity of the combined polyether, improve its foaming process, and improve the fluidity of the foam, which is beneficial to foam molding. Taking into account the needs of sustainable development strategies, the use of CFC fluorocarbon compounds, which are seriously damaging to the ecological environment, has now been restricted, and alternative blowing agents have been used.
The choice of catalyst can be a delayed catalytic system, so that the time interval between milking time and gel time is longer, which can effectively improve the fluidity of the foaming system and improve the foam performance, so as to be suitable for the production process operation. Whether the foam is uniform in the cavity, the fineness of the foam, and the closed-cell rate of the foam have a great impact on the overall thermal insulation performance of the board. These factors are related to the firmness of the foam and the cavity wall, and the dimensional stability of the foam.
Flame retardants can improve the fire resistance of foamed plastics, but flame retardants have a destructive effect on the foam during the foaming process. On the premise of ensuring the improvement of the flame retardant effect, the performance and dimensional stability of the foamed plastics are guaranteed.
