Polyurethane foam is primarily a cellular plastic. The properties of this die depends mainly on two factors, the structure and composition. The cell structure is formed by the action of blowing agents. The more the structure is fine and homogeneous, the more mechanical properties of the polyurethane foam is good. The chemical composition also between largely in its mechanical strength. A homogeneous mixture stoichiometric gives the polyurethane foam its optimum mechanical properties. Nucleation (air, CO2 or nitrogen) enters the like using a part of the mechanical expansion. When physical agents are used to form the cells, the gas phase of foamed plastic is chemically identical to that of the blowing agent. This technique has encountered difficulties of implementation, recently solved by adding the function of the miscibility of gas into a liquid through a set of changes associated with a system for mixing and homogenisation pressures of high performance.
The direct effects of nucleation:
Action on the chemical composition: The principle of nucleation is to refine the cellular structure of the foam by a combined set of actions performed on the polyol. A better mix the polyol with additives and incorporate air into very fine particles increases its reactivity, which significantly improves the quality of mixing the isocyanate / polyol and thereby optimizes a stoichiometry reaction. This feature allows a better crosslinking improves the mechanical properties of the polyurethane foam.
This machine consists of a steel framework holding all the components needed for its op-erations, such as motor pipes, pumps, valves, tanks, control panel and instruments. It is a fully autonomous system, controlled via a tactile colour screen.
The touch screen control system provides start-up, production and weekend modes as well as constant display of the measured values, faults and help.
The gas load generates a very large production of gas bubbles, such as are required, for example, for "rigid foam" applications. In this case, a gas load of over 25% is normal.
The gas particles are injected into a secondary circuit and distributed evenly throughout the raw material (polyol). A density measuring system is used to maintain and regulate the preselected gas load automatically.
Nucleation consists in installing a device for introducing air into a polyol in parallel with the buffer tank of the metering device. Together, the tank and the gas loading system constitute a closed hydraulic circuit that does not affect the characteristics of the foam in any way (flow rate, pressure, production rate...). Owing to its design, its nucleation capacity is such that production is not affected by the simultaneous filling of the tank. Its concept loop repeatedly toggles the polyol in series of static mixers, which has the effect of dividing the air bubbles into smaller particles which, by the effect of the pressure become miscible. This nucleated polyol can therefore pass into the high-pressure pump without cavitation.
The fluid to be injected with air circulates in the gas loading system, passing through the densitometer and the mixer. Constant measurement of the circuit pressures and density enable the computer to define the air load requirements. When the measurement differs from the setpoint, the gas loading system injects the air into the fluid in the form of micro bubbles. The injection sequences are carried out according to the volume of fluid to be processed.
Max. flow rate: 26 l/min
Viscosity: Polyol 100—2500 mPas at 20° C
Gas supply: 8 bar minimum—60 bar maximum
Power supply: 400 V—3 phase—50 Hz—20 ADSC01032A
Control voltage: 24 V
Dimensions: approx. length 1570 x width 900 x height 160
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